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This thesis explores the synthesis of and subsequent use of monometallic lanthanide complexes and their reductive potential for selected biomarkers. Attempts on a bimetallic complex are also reported. Chapter 1 outlines the properties of lanthanides with a focus on their photophysical and chemical behaviour, and the kinetic requirements for complexes containing lanthanides. Medical applications and discussions on the key reductive biomarkers to this thesis are also discussed. Chapter 2 explores the use of anthracene as a functional chromophore in a DO3A-based lanthanide complex, and the synthetic protocol and characterisation of these complexes by NMR, luminescence, and UV. Interaction of these complexes with singlet oxygen and irradiative stimuli is focused on in detail. Chapter 3 discusses attempts on synthesis of a bimetallic lanthanide complex based on the anthryl-functionalised DO3A complexes discussed in Chapter 2. Chapter 4 investigates synthesis and characterisation of benzoazide-functionalised DO3A lanthanide complexes. Studies on their reduction potential are undertaken using two biomarkers, and the difference in reactivity is briefly discussed. Chapter 5 reports synthesis and characterisation of DO3A lanthanide-containing complexes functionalised with nitrobenzene. Investigations into the reduction potential of these complexes to a previously chosen reductant are undertaken and discussed. Chapter 6 discusses the conclusions reached during the course of this work, and suggests possible avenues for future research. Chapter 7 contains experimental techniques for processing data, and procedures for synthesis and characterisation of these complexes.

This thesis describes the synthesis of heterobimetallic complexes which contain an unsupported bond between a group 13 and a group 11 metal (Cu, Ag, Au). While the primary focus is on bonds to aluminium, which are lesser known, the analogous gallium-coinage metal compounds are also investigated as a point of comparison. The methodology used in this work makes use of the first of a new class of nucleophilic aluminium ‘aluminyl’ anions, K2[(NON)Al]2 (NON = 4,5-bis(2,6-diisopropylanilido)-2,7-di-tert-butyl-9,9-dimethylxanthene), which is reacted with group 11 electrophiles of the form R3PMI (R = Ph, tBu, Cy) in a salt metathesis reaction. This approach gives access to rich structural variety, producing bimetallic complexes of the form (NON)AlMPtBu3, a 2:1 di(aluminyl)cuprate system, K[Cu{Al(NON)}2], and trimetallic iodide bridged complexes, (NON)Al(MPPh3)2I. These compounds are characterised by X-ray crystallography and multinuclear NMR, with spectroscopic comparisons to the heavier congeners (prepared using the gallyl reagent K2[(NON)Ga]2 giving insight into the properties of the aluminyl fragment as a metalloligand. The reactivity of the linear (NON)AlMPtBu3 series towards small molecules is then explored. The compounds in this bimetallic series readily insert carbon based electrophiles (CO2, carbodiimides) into the Al–M bond to give a complexes containing an M(CE2)Al bridging unit (E = O, NR), with an unusual μ-κ1(C):κ2(E,E′) binding mode. While the carbodiimide insertion products are stable to further reaction, it is observed that the CO2 bridged species have the potential to react onwards, and that this ability depends on the identity of the group 11 metal. (NON)Al(O2C)AuPtBu3 is inert to further reaction, while (NON)Al(O2C)AgPtBu3 reacts slowly with a second equivalent of CO2 to give a bridging carbonate complex and CO. Copper compound (NON)AlCuPtBu3 reacts rapidly even at very low temperatures, proceeding straight to the carbonate complex. The mechanism of this CO2 to CO transformation can be investigated and is found to be consistent with rate determining extrusion of CO to form a bridging Al–O–M oxide, followed by uptake of a second molecule of CO2. The behaviour of the Al–M bond towards alkynes is then investigated. Internal alkynes insert into the Al–Cu bond of (NON)AlCuPtBu3, giving (aluminylalkenyl)copper compounds with M–C bonds of differing natures. The insertion gives access to both syn and anti dimetallated alkenes, depending on the reaction conditions. It is also regioselective, producing only one regioisomer when unsymmetrically substituted alkynes are used. The mechanism of the insertion, and a subsequent isomerisation step, are investigated through kinetics studies. The differential reactivity of the (aluminylalkenyl)copper compounds is exploited by selective functionalisation with CO, which inserts only into the Cu–C bond. This results in formation of the first structurally characterised example of a copper acyl complex, a feat made possible by cooperative action of copper and the proximal aluminium centre. In all, this thesis aims to demonstrate the utility of the potassium aluminyl reagent K2[(NON)Al]2 as a means to forming direct Al–M bonds, and investigate the reactivity of such heterobimetallic compounds towards challenging small molecules.

This thesis reports on investigations into fluoroborate compounds with a view to their application in 18F-PET tracer design. The principle aim was to understand how advances could be made to the functionalisation of fluoroborate compounds for bioconjugation, in addition to improving their hydrolytic stability and optimising synthesis via efficient fluoride uptake routes. Chapter 3 reports on investigations into the synthesis and fluoride binding capabilities of 1,8-bis(boryl)-naphthalene scaffolds featuring boronic acid and ester functional groups. These bidentate “ligands” were investigated for potential thermodynamic enhancement that may be attained by chelating fluoride in such a structure, and the opportunity this offered for hydrolytically robust fluoride complexes. The diboronic acid system is established to be incompatible for this application due to the formation of an exceptionally robust intramolecular anhydride that effectively blocks the binding pocket. An unsymmetrical framework featuring a single boronic ester group is demonstrated to be suitable for chelation, although fluoride binding was subsequently compromised by a thermodynamically driven, functional group rearrangement that positions fluoride in a more labile terminal position, with a B–O–B bridge again being generated. Chapter 4 explores how highly robust N-heterocyclic carbene boron trifluoride adducts may be diversified to facilitate a range of methods for bioconjugation. The modular design of N-heterocyclic carbenes is exploited in this endeavour. Thus, a series of adducts has been synthesised featuring systematic variation of the carbene backbone, and the impact on their hydrolytic stability assessed. The preparation of a N-alkyne appended NHC-BF3 derivatives is also described, and their bioconjugation to a folic acid derivative detailed. Chapter 5 describes the investigation of carbene stabilised boron complexes and their fluoride binding reactions. Three-coordinate carbene-stabilised catecholato-boreniums have been investigated together with related series of four-coordinate complexes featuring either an additional anionic or neutral donor group. Systematic variation of the carbene donor and the leaving group substituent have been used to tune the rate of fluoride binding by these complexes, in addition to their hydrolytic stability. Neutral and cationic boron complexes are thus explored, with the four-coordinate boronium cations being determined to offer the greatest scope for optimising reactivity and stability. Careful choice of the secondary donor (based on pKa) offers a workable compromise between the kinetics of fluoride uptake at 60 °C and the stability of the boronium precursor to hydrolysis. Thus, systematic optimisation allows rapid, promoter-free fluoride binding to be achieved with a bench-stable boronium complex.

Anions are ubiquitous in nature. In order to understand them in their natural setting, this thesis focusses on developing lanthanide complexes as hosts for the recognition of biologically relevant anions, particularly chloride and sialic acid. Chapter-I introduces lanthanide chemistry encompassing macrocyclic complexes, luminescence, and MRI. An account of anion recognition and lanthanide complexes used as hosts for biologically relevant anions are reviewed. Chapter-II focuses on developing receptors for chloride recognition. The concept of binuclear lanthanide complexes, bridged by flexible ethane/propane spacer, for chloride recognition is envisioned. The proposed complexes are synthesised, and their anion binding properties are studied by luminescence, NMR spectroscopy, and X-ray crystallography. The study demonstrates the versatility of these binuclear complexes as the strongest chloride binding receptor to function in water and buffers to date. Thus, the work described here, hits a new milestone in anion coordination chemistry, ameliorating detailed exploration. Chapter-III builds on the drawbacks from these neutral complexes towards anion binding, and proposes tryptophan-conjugated cationic binuclear complexes for halide recognition. Initial studies show promising results towards halide recognition in water from this cationic coordination complex. Chapter-IV revisits a ditopic approach of arylboronate-conjugated lanthanide chelates for sialic acid recognition, a tumour biomarker. However, the complexes suffer from protodeboronation, leading to the cleavage of boronic acid which is reported for the first time with structural evidence. The resulting boron free complex binds to L-lactate and D-gluconate. Chapter-V employs the ditopic approach, but with the incorporation of rigid anthracene and dansyl spacers between them, to improve the stability of the arylboronate during complexation. However, the anthracene-based receptor proved synthetically challenging. The success in making the dansyl-functionalised ligand extents the possibility of investigating sialic acid binding. Chapter-VI summarises the work embodied in this thesis and Chapter-VII describes the complete experimental procedures followed in accomplishing the results reported in Chapters II-V.

Chronic inflammation is prevalent in society with a wide range of inflammatory diseases, such as rheumatoid arthritis and inflammatory bowel disease, as well as association with cancer, strokes, and neurodegenerative conditions. Due to the complexity in the inflammatory pathways and a lack of understanding of those processes, there are limited therapeutic options available that aim to resolve the causes of inflammation, with most treatments instead aiming to manage symptoms. More bespoke imaging agents are required to help advance our understanding of the fundamental processes governing these disease states. To overcome current imaging limitations such as quantification, correlation, depth penetration and resolution quality, this work takes a multimodal molecular imaging approach to study one type of immune cells, macrophages, that are of particular importance in rheumatoid arthritis. Such methods aim to aid the non-invasive characterisation of disease phenotypes and therapeutic response in inflammatory diseases such as IBD and rheumatoid arthritis. The general structure of selective imaging probes is an imaging moiety, a targeting group to localise at a specific site and a linker group to attach the two. The work within this thesis focusses on designing a toolkit of imaging probes that target macrophages by using folate and tuftsin derivatives to target receptors with macrophage selective expression. A variety of imaging modalities are explored in this work such as lanthanide luminescence, magnetic resonance and photoacoustic, with the aim to permit the choice of the most appropriate modality required for a given spatial resolution, scale, and depth penetration. In addition, different bioconjugation strategies have been investigated, such as amide linkages and azide-alkyne cycloadditions, to enable access to a wider variety of macrophage imaging agents. By using a toolkit of molecular components that can be easily combined, this work demonstrates preliminary work for luminescent microscopy, magnetic resonance, and photoacoustic imaging to enable the study of macrophage populations in tissue and model systems. Chapter 1 outlines the processes governing inflammation and the current methods of imaging inflammation. It provides a general overview of the different imaging modalities, with a specific focus on lanthanide chemistry and its photophysics, magnetism and stability in relation to its in vivo imaging. Moreover, the suitability of the targeting moieties – folate and tuftsin – are discussed and the prior work in these areas. Chapter 2 outlines the synthesis, paramagnetic NMR spectroscopy and photophysical characterisation of alkyne appended DO3A derivatives. The purpose of these alkynes is for use in bioconjugation to the targeting moieties with an azide functionality for use in CuAAC and SPAAC. Chapter 3 describes the synthesis of multiple terbium-folate conjugates using solid-phase synthesis, as well as the generation of folate-azides for conjugation to the alkynes discussed in chapter 2. The NMR spectroscopy and photophysical properties of these terbium-folate conjugates are discussed. Chapter 4 details the synthesis of lanthanide-tuftsin conjugates for use in optical and magnetic resonance imaging. The relaxivity and cell diffusion NMR spectroscopy of the gadolinium complexes were studied in blood plasma and whole blood and was compared to a commercially available non-specific gadolinium complex, DOTAREM. Chapter 5 discusses the preparation of macrophage-targeted photoacoustic probes and their optical properties. The probes are investigated for their photoacoustic properties and stability. Chapter 6 provides a summary of work and conclusions that can be drawn, with opportunities for future work proposed. Finally, chapter 7 contains the experimental procedures.

This thesis explores the design, synthesis, optoelectronic properties, and photocatalytic testing of copper(I) complexes with a two- or three-coordinate geometry bearing N-heterocyclic carbene ligands. Our design strategies aim to avoid the failings of four-coordinate copper(I) complexes which are prone to Jahn-Teller distortion in the excited state. The first chapter provides an overview of the fundamental photophysical properties of transition metal complexes and an introduction to bimolecular energy and electron transfer processes. A mini-review of Earth-abundant photocatalysts is presented. Special attention will then be devoted to describing the design principles of copper(I) based photocatalysts (PCs). We begin by describing the photophysical and electrochemical properties of four-coordinate copper(I) complexes, followed by the design and applications of copper(I) complexes as PCs. Next, we provide a summary of the development of two- and three-coordinate copper(I) complexes, describing their photophysical properties and applications. Chapter 2 describes the synthesis, characterisation and optoelectronic properties of seven three-coordinate copper(I) N-heterocyclic carbene (NHC) complexes bearing N^N ligands, of the form of [Cu(IPr)(N^N)]PF₆ (where IPr is 1,3-Bis(2,6-diisopropylphenyl)imidazolium, and N^N is phen = 1,10-phenanthroline, bpy = 2,2’-bipyridine, dpa = 2,2’-dipyridylamine, mdpa = N-methyl-2,2’-dipyridylamine, dpym = di(pyridin-2-yl)methane, phdpym = 2,2'-(phenylmethylene)dipyridine, fludpym = 2,2'-(9H-fluorene-9,9-diyl)dipyridine). Six complexes underwent successful preliminary photocatalytic testing in two mechanistically distinct photocatalysis reactions: an Atom Transfer Radical Addition (ATRA) photoinduced electron transfer (PET) reaction between an alkyl halide and an alkene; and photoinduced energy transfer (PEnT) reaction of a vinyl azide to a vinyl nitrene, which subsequently rearranges to form a pyrrole. The complex [Cu(IPr)(phen)]PF₆ performed best in the ATRA reaction (77% NMR yield) out of six complexes tested, while complex [Cu(IPr)(phdpym)]PF₆ performed best in the PEnT reaction (59% NMR yield vs 66% obtained with [Cu(dmp)(BINAP)]BF₄). Chapter 3 reports the synthesis, characterisation and optoelectronic properties of a series of three-coordinate copper(I) NHC complexes bearing a dpa ligand, of the form [Cu(NHC)(dpa)]PF₆. Three complexes underwent preliminary photocatalytic testing, however their performance as PCs was poor. Chapter 4 reports the first example of a neutral linear two-coordinate Cu(I) complex Cu(IPrBIAN)(Cz) bearing an IPrBIAN NHC ligand, and after investigation of its optoelectronic properties, it was successfully applied as a PC in a proof-of-concept PET ATRA reaction (52% NMR yield). Cu(IPrBIAN)(Cz) also exhibited interesting dual emission properties in solution; this is seen as separate emission depending on excitation source for most solvents, and is especially strong in chloroform solution. The synthesis, characterisation, and optoelectronic properties of further derivatives of this complex bearing 3,6-substituted carbazolate ligands were also investigated. The final conclusions chapter summarises the results of each chapter and brings focus to the overarching aims and themes of the thesis. This chapter identifies key areas for future work in the field of two- and three-coordinate copper(I) complexes as photocatalysts, specifically the need to improve PC stability, investigate reaction mechanisms, and correlate structure-property relationships with photocatalytic performance. A need for standardisation of photocatalysis reaction set-ups is identified as a requirement for reproducibility of results within the field of photocatalysis.

Metallodrug discovery has evolved in recent years, yielding several compounds in the clinic for therapeutic and medical imaging diagnostic applications. As reviewed here, several research groups in well-established medicinal inorganic chemistry groups are consistently generating high-quality SAR data representing an ideal starting point in the use of computational methods to advance the development of new drugs. Although there are representative chemical structures of metallodrugs in public databases annotated with biological activity, there is currently no public compound database dedicated to metallodrugs. Here, we also discuss the significance, viability, applications and challenges of developing a public compound database of metallodrugs - with consistent representation of metallodrug structure being a crucial obstacle. A curated metallo-compound database would substantially benefit metallodrug discovery and development.

Photoredox catalysis constitutes a very powerful tool in organic synthesis, due to its versatility, efficiency, and the mild conditions required by photoinduced transformations. In this paper, we present an efficient and selective photocatalytic procedure for the aerobic oxidative dehydrogenation of partially saturated N-heterocycles to afford the respective N-heteroarenes (indoles, quinolines, acridines, and quinoxalines). The protocol involves the use of new Ir(III) biscyclometalated photocatalysts of the general formula [Ir(C^N)2(N^N′)]Cl, where the C^N ligand is 2- (2,4-difluorophenyl)pyridinate, and N^N′ are different ligands based on the 2-(2′-pyridyl)benzimidazole scaffold. In-depth electrochemical and photophysical studies as well as DFT calculations have allowed us to establish structure−activity relationships, which provide insights for the rational design of efficient metal-based dyes in photocatalytic oxidation reactions. In addition, we have formulated a dual mechanism, mediated by the radical anion superoxide, for the above-mentioned transformations., We acknowledge the financial support provided by the Spanish Ministerio de Ciencia, Innovación y Universidades (RTI2018- 100709-B-C21 and CTQ (QMC)-RED2018-102471-T), Consejería de Educación de la Junta de Castilla y León and FEDER (BU087G19 and BU067P20), and Junta de Comunidades de Castilla-La Mancha-FEDER (JCCM) (grant SBPLY/19/ 180501/000260). I.E. acknowledges his fellowship to both the European Social Fund and Consejería de Educación de la Junta de Castilla y León (EDU/1100/2017). We are also indebted to J. Delgado, P. Castroviejo, and M. Mansilla (PCT of the Universidad de Burgos) for technical support, G. GarcíaHerbosa for providing us access to CV equipment, and J. V. Cuevas-Vicario for support with Gaussian.

We present the first example of a silver double-tetranuclear cluster helicate [Ag4L2]2 obtained from a bisthiosemicarbazone ligand using electrochemical synthesis. This cluster helicate undergoes a rare desulfurization process in chloroform giving rise to a cationic silver dihelicate [Ag2(H2L)2]SO4. This is the first silver mediated desulfurization reaction., FEDER cofunded-grants: from Consellería de Cultura, Educación e Ordenación Universitaria, Xunta de Galicia, 2017 GRC GI-1682 (ED431C 2017/01), 2018 GRC GI-1584 (ED431C 2018/13), MetalBIO Network (ED431D 2017/01), Ministerio de Ciencia, Innovación y Universidades, METALBIO (CTQ2017-90802-REDT) and MultiMetDrugs (RED2018-102471-T).

CO2 reduction has drawn much attention globally in the development of new processes and technology for avoiding the impact of serious climate change. On the other hand, the fossil fuel as energy resources cannot be easily replaced in order to greatly reduce CO2 emission. CO2 utilisation has been widely investigated in many manufacture/industries areas. This chemical conversion of CO2 is not only adding value to the process of CO2 reduction but also has economic and environmental benefits. Using CO2 as a feedstock in the synthesis of high-demand chemicals in modern chemical industry would have a high economic value. However, due to the stability of CO2, a highly effective heterogeneous catalyst is required in order to provide pathways to the synthesis of important chemicals in this way. In this work, CrOx-based catalysts supported on ZrO2 have been developed and investigated for the dehydrogenation of propane using CO2 with various metal oxides (Zn, Mn, Ca) as promoters. In addition, a different catalyst preparation method the “one-pot synthesis” has been used to develop a more effective catalyst than those in which the metal is added to a support in a conventional way. Another exciting part of the work is the regeneration process of deactivated catalysts for recovering their catalytic ability, thus extending their catalytic lifetime. Based on this work, we show that the one-pot catalysts provide different catalyst surface morphologies, structures, and catalytic properties as compared to the conventional impregnation catalysts. The dominated ZrO2 species changed from monoclinic phase in the impregnation catalysts to tetragonal phase in one-pot catalysts. It also reveals a more uniform and highly dispersed catalytically CrOx active phase in which the CrOx species can be involved in the reaction more effectively than the corresponding impregnated catalysts. In addition, one-pot catalyst showed an increase amount of the active Cr(VI) species. The introduction of a CaO promoter, the catalyst shows different surface acidity and basicity. In addition, the 2Cr/Ca-ZrO2 shows an increase in both the overall propane conversion and propylene selectivity. The CaO promoter helps the process to reach 18% of propane conversion with 20% propylene yield and keep for 4-5 hours during the process. After the process, the propane conversion reduces to 10%, 15% product yield but with still about 93% propylene selectivity. Moreover, it also reduces the level of detrimental carbon deposition on the catalyst particles leading to enhanced stability and performance. In addition, the regeneration process can recover the catalytic ability for a continuous CO2-PDH process which shows the good potential for the long-term stable performance of the one-pot catalysts. The development of novel catalytic system for CO2-PDH make this process more attractive and effective not only in reducing net CO2 emission by using it to produce useful chemical products but also by helping reach the demand for these (propylene in this case). The work suggests that further development of catalysts for this and similar processes is desirable.

Low-valent group 15 compounds stabilized by pincer ligands have gained particular interest, given their direct access to fine-tune their reactivity by the coordination pattern. Recently, bismuth has been employed in a variety of catalytic transformations by taking advantage of the (+1/+3) redox couple. In this work, we present a detailed quantum–chemical study on the electronic structure of bismuth pincer complexes from two different families, namely, bis(ketimine)phenyl (NCN) and triamide bismuthinidene (NNN). The use of the so-called effective oxidation state analysis allows the unambiguous assignation of the bismuth oxidation state. In contrast to previous studies, our calculations suggest a Bi(+1) assignation for NCN pincer ligands, while Bi(+3) character is found for NNN pincer complexes. Notably, regardless of its oxidation state, the central bismuth atom disposes of up to two lone pairs for coordinating Lewis acids, as indicated by very high first and second proton affinity values. Besides, the Bi–NNN systems can also accommodate two Lewis base ligands, indicating also ambiphilic behavior. The effective fragment orbital analysis of Bi and the ligand allows monitoring of the intricate electron flow of these processes, revealing the noninnocent nature of the NNN ligand, in contrast with the NCN one. By the dissection of the electron density into effective fragment orbitals, we are able to quantify and rationalize the Lewis base/acid character., Effective oxidation state analysis sheds light on the electronic structure of chemical systems. The oxidation state of bismuthinidene pincer complexes can be assigned as Bi(+1) or Bi(+3) depending on the nature of the ligands. Despite this assignation, the reactivity pattern as Lewis base or acid is similar. The occupation of the effective fragment orbitals gives a straightforward method to quantify the reactivity.

Polymers are extensively used in food and beverage packaging to shield against contaminants and external damage due to their barrier properties, protecting the goods inside and reducing waste. However, current trends in polymers for food, water, and beverage applications are moving forward into the design and preparation of advanced polymers, which can act as active packaging, bearing active ingredients in their formulation, or controlling the head-space composition to extend the shelf-life of the goods inside. In addition, polymers can serve as sensory polymers to detect and indicate the presence of target species, including contaminants of food quality indicators, or even to remove or separate target species for later quantification. Polymers are nowadays essential materials for both food safety and the extension of food shelf-life, which are key goals of the food industry, and the irruption of smart materials is opening new opportunities for going even further in these goals. This review describes the state of the art following the last 10 years of research within the field of food and beverage polymer's applications, covering present applications, perspectives, and concerns related to waste generation and the circular economy.

This thesis describes the design, synthesis and testing of novel anion host architectures which exploit hydrogen, halogen, and chalcogen bonding for the purpose of selective and stimuli-responsive anion transport across lipid bilayer membranes. Chapter 1 introduces the field of anion supramolecular chemistry, with particular focus on areas of relevance to this thesis, namely transmembrane anion transport. Chapter 2 describes the design, synthesis and testing of monodentate halogen and hydrogen bonding anion transporters. Chapter 3 describes the design, synthesis and testing of bidentate halogen and chalcogen bonding anion transporters with non-protonophoric activity and carriers with higher denticity. Chapter 4 describes the design, synthesis and testing of photo-caged, stimuli-responsive anion transporters. Chapter 5 describes the experimental procedures used within this research and details the characterisation of compounds presented in Chapters 2–4. Chapter 6 summarises and concludes this thesis. The Appendix holds all the original data for the 1H NMR titration experiments and the anion transport assays.

Over the years, biocatalysis has evolved as an extremely useful tool for synthetic applications due to the incredible selectivity it offers under relatively mild reaction conditions. With the advent of directed evolution and enzyme engineering, new reactivities previously unknown in nature are also being discovered by scientists. One of the main factors that determines the cost and efficiency of many biocatalytic reactions is their cofactor regeneration system. Cofactors are helper molecules that aid an enzyme to sustain catalysis. Their complex structure makes them prohibitively expensive such that their stoichiometric addition for a biocatalytic reaction is not viable. Cofactor regeneration involves the recycling of a catalytic quantity of the cofactor over and over again using a catalyst. Cofactor regeneration techniques for the nicotinamide cofactors have been widely resolved in the past to an extent that some enzymes dependent on these cofactors have found application in industry. This thesis looks at ways to recycle another useful class of cofactors – the flavins. Preliminary efforts to regenerate the deazaflavin cofactors are also presented. Enzymes that rely on flavin cofactors have valuable synthetic utility, however, their application in industry is not well established perhaps due to the lack of efficient recycling methods. This project resulted in an exciting discovery that hydrogenases can reduce flavins under H2, an atom economical reductant. The robust nature and exceptional stability of the hydrogenase, Hyd1 was exploited to supply reduced flavins for ene-reductases and nitroreductases to accomplish H2-driven C=C double bond reductions and nitro reductions respectively with high selectivity. Thus a new application for the hydrogenase enzyme has been uncovered. Demonstration of this novel, single-enzyme flavin regeneration system for application with several useful enzymes, with benefits over current flavin recycling methods, could make this Hyd1/ flavin system a promising choice for use in industry.

This work is focused on the synthesis and characterisation of n = 2 Layered Perovskite Oxides. KNdM2O7 (M = Ta, Nb) were synthesized by a two-step cation exchange reaction from RbNdM2O7 via NaNdM2O7. The K-phases adopt a polar Im2m structure. A competition between the requirement of bonding optimization of the K+ and Nd3+-cation sites is demonstrated. A’BiNb2O7 (A’ = Rb, Li, Na, K) were synthesized and their structures were determined. All four compounds adopt noncentrosymmetric crystal structures. Comparison with the spherical Nd-analogues demonstrates that although the Rb and Li phases adopt polar structures described in the same space group, the presence of the asymmetric Bi3+ enhances the polarity in these structurers. In the NaBiNb2O7 phase, the noncentrosymmetry is generated from the 6s2 electronic configuration of the Bi3+. The KBiNb2O7 phase exhibits frequent “axis switch” stacking faults in which the (0, ½, z) stacking changes to (½, 0, z) stacking and vice versa. Members of the solid solution with composition Li2SrxCa1-xTa2O7 were synthesized and demonstrated that a structural transformation takes place from hybrid improper A21am structure to proper Pna21 structure with Ca-substitution. Some of the room temperature A21am phases in this series of compounds were shown to have a phase transition to the Pna21 structure at low temperature. Similar phase transition behaviour was observed for the Li2SrNb2O7 phase. The polarity in the Pna21 phase is driven by the SOJT effect of the 4d0-Nb5+ cation. Substitution of 4d-Nb by 5d-Ta in the Li2SrNb2O7 structure lowers the SOJT effect which lowers the stability region of the Pna21 phase. The lifting of inversion symmetry in the polar structures of Li2La(TaTi)O7 and Na2La(TaTi)O7 occurs via two different mechanisms: a trilinear coupled hybrid-improper mechanism for the Li-phase and a more conventional SOJT-driven mechanism for the Na-phase. The operation of these two different mechanisms in materials with a common La(TaTi)O7 core suggests they compete against each other, and further suggests this competition is also occurring in other hybrid-improper ferroelectric phases which contain SOJT active cations. MnCaTa2O7 was synthesized by a topochemical cation exchange reaction from Li2CaTa2O7. MnCaTa2O7 adopts a polar P21nm structure where Mn2+ cations are ordered in chequerboard arrangement. Mn2+ magnetic moments order antiferromagnetically below 56 K. Further cation exchange reactions were performed to synthesize MCaTa2O7 (M = Fe, Co, Zn). Successful synthesis of these phases indicates that the cation exchange chemistry could be used to incorporate divalent transition metal cations within the distorted double perovskite frameworks of n = 2 Ruddlesden-Popper phases.

Medicinal inorganic chemistry is a burgeoning subfield of medicinal chemistry that focuses on the development of metal-based diagnostic and therapeutic agents. This tutorial review aims to provide an introductory primer, present a timely overview of recent discoveries and identify current challenges and opportunities of the field. Three specific areas of discovery are highlighted herein. The first part focuses on metal-based radiopharmaceuticals for diagnostic and therapeutic purposes and specific design criteria for the development of radiopharmaceuticals that combine fundamental aqueous coordination chemistry with elucidation of pharmacokinetics. The second part describes approaches to photodynamic therapy with metal complexes. Here, photophysical characterization, combined with the challenge of careful control of the chemical behavior and selective biological deposition of transition metals with significant off-target toxicity, is discussed. In the third part, we summarize emerging strategies to modulate enzyme inhibition with coordination chemistry, while also highlighting the utility of the unique properties of metal ions for the characterization of mechanisms of action of these emerging diagnostic and therapeutic agents.

Cathode materials remain one of the main limiting factors for increasing the specific energy of lithium ion batteries. The reversible storage of charge on lattice oxygen, called oxygen redox (O redox), has been identified as a promising route for addressing the problem in layered and disordered rocksalt materials. Currently, several interrelated challenges, including slow kinetics, voltage and capacity fade, as well as structural changes, remain, that are investigated in this thesis. A dedicated operando cell, capable of applying significant stack pressure, was built to investigate layered lithium-rich materials. It is used to study Li1.2Ni0.13Co0.13Mn0.54O2 and Li1.2Ni0.2Mn0.6O2 using high energy-resolution fluorescence-detected X-ray absorption near edge structure (HERFD-XANES), as well as X-ray emission spectroscopy (XES). The complex interplay between bulk oxygen and transition-metal redox is analysed, and it is demonstrated that Ni is fully oxidised to Ni4+ in one compound but not the other. The structure of the disordered rocksalt Li2MnO2F is solved using a combination of neutron pair distribution function (PDF) and neutron diffraction, simultaneously fit using a Reverse Monte Carlo (RMC) approach. The capacity fade for the same material is investigated and found to be initially based on a large charge-transfer resistance, associated with the slow O redox kinetics on discharge.

This thesis explores the geometry and electronic structure of some manganese doped silicon clusters. Experimental characterisation of these clusters is severely limited. Theoretical investigations with density functional theory (DFT) yield conflicting results due to differences in the choice of functional. Hence, a combination of both theory and experiment has been employed: our experimental collaborators have measured the IR-MPD spectra of these clusters while we have used DFT calculations to explore the potential energy surfaces. For a given cluster, the vibrational spectra for low-lying isomers have been computed and compared with the measured spectrum to identify the experimentally observed isomers. The information content of the spectra has been expanded by assigning vibrational modes to various peaks and by identifying vibrational signatures. Given that there is no consensus about the choice of functional, the results have been computed with a range of functionals. The influence of functional choice on the conclusions has been studied which reveals how certain functionals stabilise structures with low vertex connectivity while others tend to favour deltahedral frameworks. Multiconfigurational self-consistent field theory (MC-SCF) has been used to get an alternative perspective on bonding in these clusters. By making use of generalised and restricted active spaces (GAS and RAS), important contributions to static correlation in these clusters have been probed. An attempt has been made to account for dynamic correlation by applying perturbation theory corrections to energies obtained by the RASSCF method. However, sufficient static correlation has not been captured in the RASSCF wavefunction to allow for a reliable perturbative treatment of the remaining, missing, correlation.

The synthesis and reactivity of compounds containing heteroatomic double bonds are described in this thesis. An overview of multiple bonds between heavier p-block elements is presented in Chapter 1, including the general synthetic routes for the formation of homoatomic and heteroatomic main group multiple bonds. The formation of group 15–element double bonds from azides and phosphaketenes is also outlined. Chapter 2 describes the synthesis of phosphagallenes through the decarbonylation of phosphaketenes. Attempts at forming analogous iminogallenes are also described herein. Chapter 3 explores the reactivity of a phosphanyl phosphagallene towards small molecules such as H2, CO2 and E–H substrates. Two different reaction pathways were found for the activation of amines, both of which were investigated by Density Functional Theory calculations. Chapter 4 expands on the synthesis of group 15–element double bonds by demonstrating the synthesis of Ge=P and Sn=P double bonds. Additionally, the reactivity of a phosphanyl phosphagermene with CO2, amines and silanes is described. Finally, Chapter 5 discusses the aim of using compounds with multiple bonds between the heavier main group elements in order to catalyse the hydroamination of substrates. Two different catalyst designs containing transition metals are targeted: a transition metal- phosphinidene complex and a transition metal substituted phosphagallene. The attempted synthesis of these compounds is described.

International audience; This Editorial by Guest Editors L. Rulíšek, M. Gruden, M. Orio and QBIC Society President R. J. Deeth summarizes the Chemistry Europe Special Collection on quantum bioinorganic chemistry, published in collaboration with the Quantum Bioinorganic Chemistry (QBIC) Society. The Collection, which recognizes of the strides made in this area of research, spans several of our portfolio journals Chemistry—A European Journal, the European Journal of Inorganic Chemistry, ChemPlusChem, ChemBioChem, ChemPhysChem, and ChemistryOpen, includes outstanding work in the field by authors across the world and we hope you enjoy reading them!

Chapter 1, Introduction: The concepts of solid-state organometallic chemistry; single-crystal to single-crystal (SC-SC) transformations; alkene isomerisation; continuous flow techniques; and para-hydrogen induced polarisation (PHIP) are introduced and given brief theoretical and practical backgrounds, each relevant to the following chapters. Chapter 2: This chapter explores the successful application of P2-type Rh-containing SMOMs in the solid- gas catalytic isomerisation of 1-butene, and describes their deployment under both batch and continuous flow conditions, achieving non-thermodynamic selectivity. In an effort to explore the chemical space, a wide variety of ligand-varied SMOMs are deployed under flow conditions: the direct tunability of solid-gas catalysis is demonstrated through ligand (R-group and tether-length) modification. Chapter 3: The SC-SC chemistry of two related systems are described: a PONOP-bound cationic Ir- containing SMOM (in collaboration with the Diamond Light Source) and a P2-type perfluorophenyl/Rh- containing SMOM. Remarkably, both of these systems undergo SC-SC transformations with shifts in periodic structure upon solid-state hydrogenation and desolvation respectively. These transformations are tracked with single-crystal X-ray diffractometry as well as solid-state NMR spectroscopy. Chapter 4: This chapter explores the NMR batch-scale solid-gas catalytic hydrogenation-polarisation of unsaturated substrates with para-hydrogen by P2-type Rh-containing SMOMs. Conducted in collaboration with the Centre for Hyperpolarisation in Magnetic Resonance, York (CHyM), the tunability of solid-gas catalysis is again demonstrated through ligand modification, yielding vastly different activities and rates of deactivation. The solid-gas hydrogenation mechanisms are elucidated with the assistance of D2 gas. Chapter 5, Experimental: The syntheses and characterisation of materials not already reported in the literature are provided, in addition to experimental methods. Chapter 6, Future Directions: The possible future directions for these projects are described in a short epilogue.

This thesis describes the development of a range of catalysts for polyester synthesis via the ring-opening copolymerisation (ROCOP) of epoxides and anhydrides. Chapter 1 provides an introduction to the ROCOP of epoxides and anhydrides, with a particular focus on catalyst development and mechanism. It also introduces the concept of switchable catalysis and describes its application to the synthesis of block polyesters. Chapter 2 details the synthesis and characterisation of a series of monometallic M(III) complexes (M = Al, Cr, Mn, Fe, Co). Their application as catalysts for the ROCOP of cyclohexene oxide (CHO) and phthalic anhydride (PA), and the ROP of decalactone (DL), is explored. The complexes featuring Al(III) and Co(III) are found to be the most active catalysts for these polymerisations. Chapter 3 details the application of the Al(III) and Co(III) complexes synthesised in Chapter 2 to the one-pot switchable catalysis reaction of CHO, PA and DL. Triblock copolymers with molar masses up to 57 kg mol-1 are synthesised. The catalytic activity of these complexes is shown to be significantly higher than previously used commercial salen catalyst systems. Chapter 4 details the synthesis and characterisation of a series of heterodinuclear Al(III)/M(I) (M(I) = Group 1 metal) complexes. All are shown to be excellent catalysts for the ROCOP of CHO and PA, with the Al(III)/K(I) and Al(III)/Rb(I) congeners being the most active. Subsequent kinetic investigations, combined with DFT calculations, result in the proposal of a mechanism where the epoxide is bound and activated by the Al(III) centre and the M(I) ion binds the carboxylate chain end. The scope of the catalysis is established for a wide range of epoxides with anhydrides and CO2. Chapter 5 details the development of an Al(III)/K(I) complex bearing organometallic coligands. It is demonstrated that use of this complex, in conjunction with bifunctional protic chain transfer agents, can yield monodisperse high molar mass polyesters via the ROCOP of vinyl-cyclohexene oxide (vCHO) and PA. The mechanical and thermal properties of the polyesters are investigated to establish the impact of increasing polymer molar mass. Chapter 6 outlines the key developments of this thesis and suggests future avenues for research that build on the work described. Chapter 7 provides experimental details for Chapters 2 – 5. An Appendix is provided that contains supplementary figures and data that support the discussion throughout Chapter 2 – 5.

This thesis describes the synthesis of inorganic semiconductor and layered zinc hydroxide colloidal nanomaterials that could, in future, be used in printing of photoelectrochemical devices. The colloidal nanomaterials are synthesised using organometallic precursors which are reacted with stoichiometric/sub-stoichiometric equivalents of ligand to provide well-defined, monodisperse, phase-controlled copper (Cu), cuprous oxide (Cu2O) and cuprous sulfide (Cu2S) nanoparticles or monolayer exfoliated layered zinc hydroxide (LZH) nanosheets. Chapter 1 provides a general introduction to the field of colloidal nanomaterials, with a comparative overview of different synthetic approaches, recent developments and applications. This is followed by a concise literature review of organometallic synthetic routes to make cuprous oxide (Cu2O), copper sulfide (Cu2-xS) and zinc oxide (ZnO) nanoparticles. It also sets out the thesis aims and objectives. Chapter 2 describes the spectroscopic, microscopy and X-ray diffraction techniques used to characterise the inorganic nanomaterials described within this thesis. Chapter 3 describes the preparation of copper and cuprous oxide nanoparticles starting from mesitylcopper(I). The chapter focusses on changing the capping ligand so as to deliver nanoparticles that are soluble in polar solvents. It also describes the most reproducible and scalable synthesis of the cuprous oxide nanoparticles. The ligand consists of an alkyl ether carboxylate namely, 2-[2-(2-methoxyethoxy)ethoxy]acetic acid, which furnish the resulting nanoparticles with high solubility in solvents such as alcohols and water. These ligands also deliver particles with consistent morphology, small size (~3 nm) and narrow dispersity. The carboxylate ligands can be readily removed after the particles are deposited onto substrates using low temperature ( Chapter 4 describes the synthesis of cuprous sulfide nanoparticles starting from organocopper precursors and by reaction with a range of sulfidising agents. Indirect routes include subjecting copper or cuprous oxide nanoparticles to anion exchange reactions or to reaction with different sulfidising reagents (i.e. S(NH4)2, S8). The preferred direct route was established by reacting mesitylcopper with bis(trimethyl silyl)sulfide or hydrogen sulfide, in the presence of substoichiometric amounts of dithiocarboxylic acid or dithiophosphoric acid as ligands, to deliver exclusively chalcocite phase (Cu2S) nanoparticles with small sizes (3-4 nm) and solubility in polar media. The chapter also presents information regarding the colloidal stability in relation to thio- or oxo-containing ligands. Chapter 5 describes a bottom-up route to make layered zinc hydroxides nanosheets via the hydrolysis of organozinc reagents in the presence of a stoichiometric quantity of carboxylic acid ligand. The route provide access to both soluble monolayer nanosheets and functional nanosheets. A series of carboxylate ligands, with alkyl ether chains, are used to make layered zinc hydroxide nanosheets showing spontaneous exfoliation and high solubilities in alcohols or water (180 mg mL-1). Altering the carboxylate ligand allows the introduction of functional groups in the layered structures. Chapter 6 describes preliminary investigation of the suitability of cuprous oxide or sulfide nanoparticles as colloidal ‘inks’ for thin-film fabrication. Different deposition techniques yield films which are assessed for homogeneity, transparency and thickness. Thin-films of cuprous oxide are tested as photocathodes. Methods to improve the film deposition and device architectures are also discussed. Chapter 7 provides an overall conclusion and outlook on the thesis. Chapter 8 describes the experimental protocols employed both in nanomaterial synthesis and outlines characterisation data.

The convenience of "no installation, available at your fingertips" of the WeChat small program makes it unique in the application of mobile terminal auxiliary experimental teaching. In order to optimize the assessment system and improve the quality and outcomes of experimental teaching, a self-designed WeChat small program was used to assist the development of the process assessment system. This system was applied to the teaching practice of "Experiment of Inorganic Chemistry" course for the first-year undergraduates majored in Biological Engineering, with the aim to promote teaching and learning by assessment. The results showed that course scores of the students who used this small program were superior to the control group and the correlation between the process assessment and final examination results was significant. These results indicated the WeChat small program assisted process assessment could effectively improve the learning outcomes of students, enable them to grasp the knowledge of Experiment of Inorganic Chemistry efficiently. The results of the questionnaire for the teachers and students also showed a high recognition of the WeChat small program assisted teaching.

Inorganic nanomaterials are defined as materials with one or more dimension within 1 – 100 nm range. These materials possess unique optical, electronic, thermo-physical, physicochemical and mechanical properties, and represent intensively explored, studied and sought-after commodities for a large variety of applications and manufacturing processes. Heterogeneous catalysts are vital for many industrial processes and often take advantage of the unique reactivity properties of nanomaterials, while battery electrode materials composed of nanomaterials are explored to solve current limitations with higher power densities via stable rapid ion and electron transport, and with high energy density via maximization of the charge storage capability. This thesis provides an insight into synthetic methods, detailed characterization and properties study, and exemplary applications of engineered 2D MoS2 nanomaterials in Li and Na ion batteries, palladium nanoparticles supported on 2D MoS2 nanosheets as heterogeneous catalysts in Suzuki and Heck C-C coupling and 1-pentyne hydrogenation reactions and sulphate functionalized titanium oxide nanoparticles as solid superacid catalysts in the esterification reaction of levulinic acid and pyruvaldehyde Cannizzaro reactions.

We report a screening study aimed to assess for the first time the air- and water-stability and the biological potential of simple metal-carbamates. These molecular metallic species are based on elements belonging to the groups 4–5, 7–9 and 11, and tin, and are easily available from inexpensive reagents. Complexes [Ag(O2CNEt2)] (13-Ag) and [Au(O2CNMe2)(PPh3)] (14-Au) resulted substantially stable in aqueous media and exhibited a potent in vitro cytotoxicity. Especially 13-Ag revealed a significant selectivity against the A549 lung adenocarcinoma and the A2780 ovarian cancer cell lines with respect to the noncancerous HEK293 cell line. Generation of ROS (reactive oxygen species) and mitochondrial membrane depolarization were recognized for 13-Ag and 14-Au; notwithstanding, the cell death mechanism is different in the two cases: apoptosis and cell cycle arrest in G0/G1 phase for 13-Ag; necroptosis and cell cycle arrest in S phase for 14-Au. Both 13-Ag and 14-Au are endowed with antibacterial activity, which is relatively stronger for 13-Ag towards Gram negative and for 14-Au towards Gram positive strains, respectively., La Caixa Foundation (LCF/PR/PR12/11070003), Consejería de Educación-Junta de Castilla y León-FEDER Funds (BU305P18), Ministerio de Ciencia, Innovación y Universidades (RTI2018-102040-B-100) and the University of Pisa (PRA_2020_39).

The agile ammonia synthesis is a collection of energy generation and storage infrastructure, which allows sustainable, local, and independent energy provision by converting renewable energy to hydrogen and ammonia, as well as in battery energy storage systems such as lithium-ion batteries. Many of these systems utilise archetypal inorganic materials, in particular due to enhanced performance from the incorporation of light-element dopants. Here, three components of the agile ammonia synthesis pathway are investigated in order to better understand the complex structure-activity relationship, in particular by using complex in-situ, in-operando, and inelastic synchrotron X-ray powder diffraction. The nitrogen doping of titania is shown to impart increased structural and electronic defects that can be exploited by photo-absorption of visible light to split water using nothing else but solar irradiance. The generation of oxygen vacancies was observed by anisotropic thermal expansion, and supported by DFT calculations and photocatalytic performance. The use of palladium nanoparticles as an electrochemical energy store by lithium intercalation has been evaluated, and in-depth phase transitions characterised. Though the intercalation process reduces the order of the host framework, the cycling capacity remains constant, indicating amorphisation does not equate to performance degradation. The location of preferential substitutional aluminium sites in zeolite ZSM-5 has been yielded by observing probe molecule adsorption, but also directly by exploiting high-contrast anomalous scattering. The results of various techniques are in broad agreement of the siting, which will have impact the understanding of zeolite synthesis and performance mechanisms.

Experimental magnetic studies performed on the [{CuLX}2 ] system (HL = pyridine-2- carbaldehyde thiosemicarbazone, X = Cl−, Br−, I−) point to the larger electronegativity in X, the lower magnitude of the antiferromagnetic interactions. In order to confirm this and other trends observed and to dip into them, computational studies on the [{CuLX}2 ] (X = Cl− (1), I− (2)) compounds are here reported. The chemical and structural comparisons have been extended to the compounds obtained in acid medium. In this regard, chlorido ligands yield the [Cu(HL)Cl2 ]·H2O (3) complex, whose crystal structure shows that thiosemicarbazone links as a tridentate chelate ligand to square pyramidal Cu(II) ions. On the other hand, iodido ligands provoke the formation of the [{Cu(H2L)I2 }2 ] (4) derivative, which contains pyridine-protonated cationic H2L + as a S-donor monodentate ligand bonded to Cu(I) ions. Crystallographic, infrared and electron paramagnetic resonance spectroscopic results are discussed. Computational calculations predict a greater stability for the chlorido species, containing both the neutral (HL) and anionic (L−) ligand. The theoretical magnetic studies considering isolated dimeric entities reproduce the sign and magnitude of the antiferromagnetism in 1, but no good agreement is found for compound 2. The sensitivity to the basis set and the presence of interdimer magnetic interactions are debated., This research was funded by the European Union H2020-LC-SC3-2020-NZE-RES-CC, NMBP-16-2020-GA 953152 and DT-NMBP-04-2020 Projects, together with the Ministerio de Ciencia, Innovación y Universidades CTQ(QMC) RED2018-102471-T MultiMetDrugs Network (Spain), PGC2018-093745-B-I00 and PID2019-111215RB-100, Consejería de Educación of Junta de Castilla y León and FEDER BU049P20 and FUNDACION BANCARIA CAIXA D. ESTALVIS I PENSIONS DE BARCELONA 001. Ministerio de Ciencia e Innovación PID2019-106644GB-I00 and Gobierno Vasco IT1458-22.

Platinum-based antitumor drugs have been used in many types of tumors due to its broad antitumor spectrum in clinic. Encouraged by the cisplatin's (CDDP) worldwide success in cancer chemotherapy, the research in platinum-based antitumor drugs has evolved from traditional platinum drug to multi-ligand and multifunctional platinum prodrugs over half a century. With the rapid development of metal drugs and the anticancer immune response, challenges and opportunities in platinum drug research have been shifted from traditional platinum-based drugs to platinum-based hybrids and the direction of development is tending toward photodynamic therapy, nano-delivery therapy, drug combination, targeted therapy, diagnostic therapy, immune-combination therapy and tumor stem cell therapy. In this review, we first exhaustively overviewed the role of platinum-based antitumor prodrugs and the anticancer immune response in medicinal inorganic chemistry based on the special nanomaterials, the modification of specific ligands, and the multiple functions obtained that are beneficial for tumor therapy in the last five years. We also categorized them according to drug potency and function. There hasn't been a comprehensive evaluation of precursor platinum drugs in prior articles. And a multifarious approach to distinguish and detail the variety of alterations of platinum-based precursors in various valence states also hasn't been summarized. In addition, this review points out the main problems at the interface of chemistry, biology, and medicine from their action mechanisms for current platinum drug development, and provides up-to-date potential strategies from drug design perspectives to circumvent those drawbacks. And a promising idea is also enlightened for researchers in the development and discovery of platinum prodrugs.

We present an experimentally guided study of film layer structure and opto-electronic properties of transition metal oxide (TMO) films. The oxide material system studied comprised the metals silicon (Si), zinc (Zn), and indium (In). The films were deposited via radio frequency magnetron sputtering (RFMS) on room-temperature Corning Eagle XG Glass (CEXG) substrates. Distinct (bi-layer (BL) vs single-layer (SL)) layer structures manifest as a function of angular distribution or pressure distance product (Greek letter 'phi') of sputtered material flux sourcing film growth. The films are amorphous, transparent and semiconducting. Experimental determination of absolute temperature (T) dependence of resistivity (Greek letter 'rho') revealed that at temperatures close to room-temperature, ionized impurity scattering (IIS) is the dominant conduction electron scattering mechanism. Thence, application of the Brooks-Herring (BH) model of IIS permitted analysis of the electronic state of the films. Thereby, the electronic state was revealed to be highly compensated. The design of experiment (DOE) and (associated) response surface analysis (RSA) frameworks were recruited from the very first stage — namely, the stage of film fabrication — of this study. This provisioned a self-referencing set of (nine) films (the ‘samples’) that are the subject of this study. The two layers of the BL films are / will-be-referred-to-as the sub-plantation layer (SPL) and the thin-film layer (TFL). The SPL is situated mediate substrate and TFL, and constitutes thereby the film-substrate interface. For consistent nomenclature, the term ‘TFL’ will be used to refer to the sole (film) layer of SL films. The layer structures of the films were established via x-ray reflectometry (XRR). The films were interrogated optically via spectroscopic ellipsometry (SE) (at room-temperature), and electrically via AC Field Hall Effect (ACFHE) measurements (between T = 10.1 K to 300 K). An account of the understanding of the film layers — viz., SPL, and TFL — as has been achieved, is as follows: ~ The sub-plantation layer (SPL) ~ We report the controlled emergence of a bonafide nanoscale layer — the SPL — at (comprising) the film-substrate interface. The determination of presence of a SPL is direct — that is, sans any assumptions, or modeling — via Fourier analysis of XRR results. We present three independent — experimental, empirical, and theoretical — threads of analysis to rationalize emergence of the SPL, as follows: > In terms of deposition process conditions under which a SPL manifests. Our semi-quantitative analysis is in terms of angular distribution or phi of the material flux sourcing film growth. Evidently, this thread of analysis is beholden to the specific physics of the deposition process, namely, RFMS. > Via RSA of SPL physical properties (SPL thickness (dSPL), SPL density (DSPL), and SPL roughness (rSPL)). This analysis reveals the following two process factors to be relevant: RF power (PRF), and process gas pressure (p). While the analysis is on the basis of experimentally observed process factors dependence of the physical properties noted, it is not beholden to the physics of the deposition process (RFMS). > Via dimensional analysis (DA) of the physical properties noted previously, in light of RFMS process. The dimensionless group for PRF (PRF*) thus determined reveals precisely the two previously noted process factors to be relevant. This analysis is ab initio. We highlight implications of our results for the industrially important problem of sputtered-film-on-substrate adhesion. Thereby, our results bear commercial promise, particularly for research and development (R&D) of flexible electronics applications. ~ The thin-film layer (TFL) ~ We quantify the semiconducting nature of the films (TFLs) on basis of optical (via SE) and electrical (via ACFHE) measurements of their room-temperature electronic properties. We interrogate the film (material system) electronic state on basis of the experimentally determined T dependences of conduction electron concentration (n) and conduction electron mobility (Greek letter 'mu'). Presence of a T-range (in the vicinity of and including room-temperature) where IIS is the dominant conduction electron scattering mechanism is established. Application of the BH model of IIS then lead to the (quantitative) determination that the electronic state is (highly) compensated. This determination — consistent with the experimentally observed anomalous oxygen content dependence of — is consistent with trap limited conduction. Thereby, we relate the electronic state to the chemistry and physics of film microstructure and material system. ~ The ready-reckoner ~ Figure 7.1 presents another and visual walk through — a ‘ready-reckoner’ — of this study. ~ Epilogue ~ This study represents new lines of investigation for the Professor Peter P. Edwards FRS ML Group.

El trabajo desarrollado se centra principalmente en estudiar la calidad de las aguas subterraneas de los acuiferos superficiales urbanos de la ciudad de Burgos, determinando ademas el grado de contaminacion y alteracion quimica que las practicas antropicas provocan en el quimismo natural de las aguas. Para ello, se han revisado y actualizado los conocimientos actuales en materia de Hidrogeologia Urbana y se ha verificado su idoneidad para el caso de la ciudad de Burgos y su entorno industrial. Se ha determinado a su vez, la composicion quimica, isotopica, microbiologica y organica de las aguas y se ha realizado un seguimiento temporal de diversos parametros fisicoquimicos en las aguas subterraneas estudiadas. Finalmente, se han cuantificado las reacciones geoquimicas mas importantes en el interior de los acuiferos mediante el empleo de tecnicas estadisticas y de modelizacion hidroquimica. palabras clave Agua Subterranea __________ Groundwater Hidrologia urbana__________ Urban Hydrology Hidroquimica______________ Hydrochemistry Analisis multivariante ______ Multivariate Analysis Contaminacion____________ Pollution

There is a clear and urgent need for rechargeable batteries of higher energy density. Alkali-ion batteries based on Li-ions are the state-of-the-art, although Na-ion may offer a cheaper alternative. In both cases the cathode imposes the biggest limitation on overall energy density. Alkali-rich cathode materials can store alkali-ions and electrons densely by invoking redox chemistry of both the transition metal (TM) and oxide ions in the lattice. However, O-redox is accompanied by voltage hysteresis, irreversible O-loss and complex structural changes. In this thesis, model Na-ion materials have been investigated to isolate and examine these phenomena. Firstly, Na0.67[Mg0.28Mn0.72]O2, with Mg2+ ions occupying the TM layer rather than alkali-ions, is studied and shown to exhibit O-redox. This reveals that ionic interactions between the TM layer substituent and O are the necessary precondition for O-redox. Secondly, by comparing the O-loss behaviours of Na0.67[Mg0.28Mn0.72]O2 and Na0.75[Li0.25Mn0.75]O2, the critical role of the TM layer substituent is revealed; when removed from the structure, the co-ordination number around O can drop below three and O-loss is triggered. Unlike Li+, Mg2+ is retained within the structure preventing O-loss. Thirdly, O-redox materials Na0.75[Li0.25Mn0.75]O2 and Na0.6[Li0.2Mn0.8]O2 are studied in parallel to understand why the former exhibits voltage hysteresis and the latter not. The preservation of the TM layer ordering scheme is shown to prevent hysteresis maintaining stable electron holes on O2- in Na0.6[Li0.2Mn0.8]O2. For Na0.75[Li0.25Mn0.75]O2, severe in-plane TM migration destroys the ordering scheme, triggered by formation of molecular O2 gas which is directly evidenced for the first time in the bulk. Reduction of O2 occurs on discharge at low voltage giving rise to hysteresis. Finally, a new Li-rich oxyfluoride, Li2MnO2F, with a stable disordered rocksalt structure is presented. Li2MnO2F stores charge utilising both Mn and O-redox with negligible O-loss demonstrating the potential of disordered rocksalts to deliver high energy densities.

This thesis examines the synthesis of novel acyclic silylenes with amido, boryl, gallyl and/or boryloxyl substituents, and their reactivities towards small molecules such as H2 , CO2 , H2O, NH3 etc. The silylene systems were also used as precursors for compounds featuring silicon-heteroatom double bonds, with a focus on the attempted synthesis of molecules featuring a Si=O moiety (silanones). Chapter 2 discusses the reactions between the gallyl anion [(DippNCH)2Ga] - and Si(II) precursors such as IDipp·SiCl2 and (NTMSDipp)(IiPrMe)SiCl. While an unexpected silyl anion formed when IDipp·SiCl2 is used, a novel NHC stabilized silylene can be synthesized by metathesis between [(DippNCH)2Ga]- and (NTMSDipp)(IiPrMe)SiCl. The gallyl-substituted silylene reacts with N2O, however, only a silyl migrated product can be isolated instead of the expected silanone. The reaction between Cy2NSiBr3 and [(DippNCH)2B] - , in attempt to install an amido substituent on a potential silylene system without a labile N-SiMe3 moiety, results instead in a C‒H activation product. Chapter 3 reports the synthesis of a novel bisboryloxysilylene, together with its heavier Ge, Sn and Pb congeners (the latter in collaboration with Dr Ying Kai Loh). Structural parameters of these tetrylenes obtained by X-ray crystallography, including the E‒O, O‒B bond distances and O-E-O, E-O-B bond angles (E = Si, Ge, Sn or Pb) show a trend consistent with expected periodic trend for group 14 elements, resulting from relativistic effects and increasingly poor s-p mixing on descending group 14. Further investigation involves studies of the reactivity of the bisboryloxysilylene fowards small molecules possessing an E‒H bond (E = H, N or O). Although no reaction is detected with H2, the silylene is able to activate the polar E‒H bonds in water, ammonia and tert- butyl amine. Such processes most likely occur through a three-molecule transition state as shown by DFT calculations. Chapter 4 explores the possibilities of synthesizing Si=E (E = C, N, O or Se) containing compounds using the bisboryloxysilylene as the precursor. The reaction between the silylene and N2O generates the first example of a silahyponitrite, which can be regarded as a masked silanone (by N2O) as the bound N 2 O can easily be substituted in reactions with CO2 and Ph3P=O. When the silylene is treated with an excess amount of selenium, a novel tetraselenosilolane can be isolated. Three out of the four selenium atoms in this compound can be removed by adding Ph3P to generate a silaselenone. Attempts have been made to synthesize a Si=N or Si=C double bond. In the former case Me3SiN3 was used as the source of Me3SiN. However, this reaction only gives a two-fold addition product, a silaazide. In the latter case Ph3P=CH2 was utilized to act as a :CH2 transferring agent. The reaction proceeds instead via a [4+1] cycloaddition process, yielding a dearomatized silaheterocyclic compound.

Three neutral Pt(II) complexes containing 1-Methylimidazole and the antifungal imidazolyl drugs Clotrimazole and Bifonazole have been prepared. The general formula of the new derivatives is [Pt(κ2-(C^N)Cl(L)], where C^N stands for ppy = 2-phenylpyridinate, and L = 1-Methylimidazole (MeIm) for [Pt-MeIm]; L = Clotrimazole (CTZ) for [Pt-CTZ] and L = Bifonazole (BFZ) for [Pt-BFZ]). The complexes have been completely characterized in solution and the crystal structures of [Pt-BFZ] and [Pt-CTZ] have been resolved. Complexes [Pt-MeIm] and [Pt-BFZ] present higher cytotoxicity than cisplatin in SW480 (colon adenocarcinoma), A549 (lung adenocarcinoma) and A2780 (ovarian cancer) cell lines. [Pt-MeIm] shows the highest accumulation in A549 cells, in agreement with its inability to interact with serum albumin. By contrast, [Pt-CTZ] and [Pt-BFZ] interact with serum proteins, a fact that reduces their bioavailability. The strongest interaction with bovine serum albumin (BSA) is found for [Pt-BFZ], which is the least internalized inside the cells. All the complexes are able to covalently interact with DNA. The most cytotoxic complexes, [Pt-MeIm] and [Pt-BFZ] induce cellular accumulation in G0/G1 and apoptosis by a similar pathway, probably involving a reactive oxygen species (ROS) generation mechanism. [Pt-BFZ] turns out to be the most efficient complex regarding ROS generation and causes mitochondrial membrane depolarization, whereas [Pt-MeIm] induces the opposite effect, hyperpolarization of the mitochondrial membrane. On the contrary, the least cytotoxic complex, [Pt-CTZ] cannot block the cell cycle or generate ROS and the mechanism by which it induces apoptosis could be a different one., La Caixa Foundation (LCF/PR/PR12/11070003), Consejería de Educación-Junta de Castilla y León-FEDER (BU042U16-BU305P18), Ministerio de Ciencia, Innovación y Universidades (RTI2018-102040-B-100). M.V. is grateful for the financial support received from the Consejería de Educación-Junta de Castilla y León-FEDER (BU042U16-BU305P18).

An important challenge in the field of anticancer chemotherapy is the search for new species to overcome the resistance of standard drugs. An interesting approach is to link bioactive ligands to metal fragments. In this work, we have synthesized a set of p-cymene-Ru or cyclopentadienyl-M (M = Rh, Ir) complexes with four chrysin-derived pro-ligands with different -OR substituents at position 7 of ring A. The introduction of a piperidine ring on chrysin led to the highly cytotoxic pro-ligand HL4 and its metal complexes L4-M (SW480 and A549 cell lines, cytotoxic order: L4-Ir > L4-Ru ≈ L4-Rh). HL4 and its complexes induce apoptosis and can overcome cis-platinum resistance. However, HL4 turns out to be more cytotoxic in healthy than in tumor cells in contrast to its metal complexes which displayed higher selectivity than cisplatin towards cancer cells. All L4-M complexes interact with double stranded DNA. Nonetheless, the influence of the metal is clear because only complex L4-Ir causes DNA cleavage, through the generation of highly reactive oxygen species (1O2 ). This result supports the hypothesis of a potential dual mechanism consisting of two different chemical pathways: DNA binding and ROS generation. This behavior provides this complex with a great effectivity in terms of cytotoxicity, Spanish Ministerio de Ciencia, Innovación y UniversidadesFEDER (RTI2018-100709-B-C21 and RTI2018-102040-B-100), Junta de Comunidades de CastillaLa Mancha-FEDER (JCCM) (grant SBPLY/19/180501/000260), Junta de Castilla y León-FEDER (BU087G19 and BU305P18), “la Caixa” Foundation (LCF/PR/PR12/11070003), as well as by UCLMFEDER (grants 2019-GRIN-27183 and 2019-GRIN-27209).

Heterogeneous catalysis plays an important role in the pharmaceutical and petrochemical industries. Due to the poor chemical selectivity in many processes, it is essential to design novel catalysts to resolve this problem. Recently, interstitially modifying transition metal NPs with light elements has become a potential strategy for adjusting surface energy and tuning catalytic activity. However, this new class of catalysts remains relatively unexplored due to a lack of adequate characterisation evidence. Herein, the work presented in this thesis continues the structural characterisation of the Pd-intB/C and Pd-intLi/C, reported from previous work, by using a novel combination of analytical techniques that span from the atomic to the macro level. Initially, these characterisations showed that after B and Li incorporation the Pd lattice maintains a face-centred cubic structure, but tolerates structural distortion. These structural distortions can further result in the local formation of the HCP structure. Additionally, the combination of STEM-EELS and ptychography was attempted to directly observe the presence of B and Li at the atomic level. Meanwhile, in order to broaden the scope of the light element modified catalyst family, attempts were made to alloy Li into the Pt host metal system. It was found that the unit cell of the Pt contracts after thermal treatment at elevated temperature, indicating the formation of the Pt-subLi nano bimetallic alloy. The combination of XPS and ssNMR confirms the presence of Li in the metal framework, in addition to the SXRD. The STEM-ADF imaging reveals the presence of the Pt7Li. Seemingly, this is the first report of Pt-Li based NPs synthesis to date. This catalyst displays premium 2,5-bis(hydroxymethyl)furan (BHMF) selectivity when catalysing HMF hydrogenation; this is due to the Li blocking specific, undesired reaction pathways. It is anticipated that such an in-depth investigation will help influence the future design and characterisation of novel, light element alloyed systems.

Inorganic materials have essential roles in society, including in building construction, optical devices, mechanical engineering and as biomaterials1–4. However, the manufacture of inorganic materials is limited by classical crystallization5, which often produces powders rather than monoliths with continuous structures. Several precursors that enable non-classical crystallization—such as pre-nucleation clusters6–8, dense liquid droplets9,10, polymer-induced liquid precursor phases11–13 and nanoparticles14—have been proposed to improve the construction of inorganic materials, but the large-scale application of these precursors in monolith preparations is limited by availability and by practical considerations. Inspired by the processability of polymeric materials that can be manufactured by crosslinking monomers or oligomers15, here we demonstrate the construction of continuously structured inorganic materials by crosslinking ionic oligomers. Using calcium carbonate as a model, we obtain a large quantity of its oligomers (CaCO3)n with controllable molecular weights, in which triethylamine acts as a capping agent to stabilize the oligomers. The removal of triethylamine initiates crosslinking of the (CaCO3)n oligomers, and thus the rapid construction of pure monolithic calcium carbonate and even single crystals with a continuous internal structure. The fluid-like behaviour of the oligomer precursor enables it to be readily processed or moulded into shapes, even for materials with structural complexity and variable morphologies. The material construction strategy that we introduce here arises from a fusion of classic inorganic and polymer chemistry, and uses the same cross-linking process for the manufacture the materials. The crosslinking of oligomeric precursors, controlled by a capping agent, enables the production of moulded crystalline calcium carbonate with continuous structures.

In order to improve their bioapplications, inorganic nanoparticles (NPs) are usually functionalized with specific biomolecules. Peptides with short amino acid sequences have attracted great attention in the NP functionalization since they are easy to be synthesized on a large scale by the automatic synthesizer and can integrate various functionalities including specific biorecognition and therapeutic function into one sequence. Conjugation of peptides with NPs can generate novel theranostic/drug delivery nanosystems with active tumor targeting ability and efficient nanosensing platforms for sensitive detection of various analytes, such as heavy metallic ions and biomarkers. Massive studies demonstrate that applications of the peptide–NP bioconjugates can help to achieve the precise diagnosis and therapy of diseases. In particular, the peptide–NP bioconjugates show tremendous potential for development of effective anti-tumor nanomedicines. This review provides an overview of the effects of properties of peptide functionalized NPs on precise diagnostics and therapy of cancers through summarizing the recent publications on the applications of peptide–NP bioconjugates for biomarkers (antigens and enzymes) and carcinogens (e.g., heavy metallic ions) detection, drug delivery, and imaging-guided therapy. The current challenges and future prospects of the subject are also discussed.

Advanced studies of structures and dynamics of functional materials based on metal-organic frameworks (MOFs) showing exceptional stimuli-driven properties is of strong current interest for the design of next-generation smart materials, especially for sorption-based applications such as gas storage, energy storage, controlled drug delivery, and molecular sensing, to name but a few. State-of-the-art diffraction and spectroscopy in conjunction with theoretical calculations are one of the most powerful approaches to achieve these detailed analyses at a molecular level. This thesis aims to study mechanistic aspects of stimuli-responsive behaviours responsible for a distinctive stepwise ammonia (NH3) adsorption in the defect-rich Zr-based metal-organic frameworks (MOFs), namely UiO-67 and its isostructural UiO-bpydc, both experimentally and computationally. In Chapter 3, high-resolution neutron and synchrotron diffractions along with Rietveld refinement and density functional theory (DFT) calculations have been used to characterise the binding domains and the interactions of NH3/ND3 with defect-rich UiO-67 and UiO-bpydc containing biphenyl dicarboxylate and bipyridine dicarboxylate linkers, respectively. The results establish that the dramatic alteration of stepwise adsorption processes is closely associated with hydrogen bonding network between NH3/ND3 and the frameworks at the disordered/defective trigonal and lozenge pore windows of the materials without significant change in pore volume and unit cell parameters. Specifically, UiO-bpydc is possible to make stronger and more extensive hydrogen bonding using pyridine sites of the linker than in UiO-67. These molecular controls lead to stimulus-tailoring properties such as gate-controlled porosity by dynamic linker flipping, disorder, and structural rigidity which are further confirmed by temperature-dependence of in situ structural analyses accompanied with guest-induced rotational motions of the organic linkers studied by DFT in Chapter 4. To get deeper insights into the interesting NH3-induced stepwise adsorption, the dynamic features of the MOF-NH3 systems have been further investigated by using advanced inelastic neutron scattering (INS), quasi-elastic neutron scattering (QENS) in conjunction with theoretical calculations. Guest-induced linker stiffening reflected by the suppression of lattice motions of the host frameworks upon NH3 adsorption is achieved, which exhibits greater effect in the UiO-bpydc case. More excitingly, analysis of INS difference spectra reveals heterogeneous dynamics of the trapped NH3 depending on MOF functionality and gas loading. For the UiO-67, the well-ordered NH3 molecules primarily adsorbed at μ3-OH have more feasibility to undergo progressive interactions with the incoming NH3 molecules, signifying its more accessible porous structure for NH3 inclusion due to the lack of guest-stimulated pore blocking conversely observed in the UiO-bpydc. QENS study elucidates negligible mobility of NH3 in both MOFs at the lowest dosage, indicative of the similar localised diffusion caused by strongly bound NH3 at the μ3-OH sites of the hosts. On the other hand, the NH3 diffusivities in these frameworks become distinct at higher NH3 uptake where the stepped adsorption occurs. This observation points toward the confined NH3 molecules experiencing a diversity of either pore environments or host-guest interactions.

This thesis examines the synthesis and the reactivity of both novel and previously reported intramolecular dimethylxanthene, dimethylthioxanthene and acridan derived frustrated Lewis pairs (FLPs). Moreover, it also reports on novel acridan-based Lewis bases and acids, and the subsequent reactivity of such species within intermolecular FLPs Chapter 1 describes the background of FLPs including the history of FLPs, and the literature studies on the reactivity of FLPs in small molecules activation/captures and catalysis. Chapter 2 reports all the experimental methods used in this thesis and the preparation of dimethylthioxanthene and acridan backbone precursors. Chapter 3 introduces an improved method for the preparation of intramolecular dimethylxanthene derived FLPs featuring Lewis acid/base pairs of -B(C6F5)2/-PPh2 and -B(C6F5)2/-PiPr2. This synthesis proceeds through isolated lithium complexes and not only gives higher overall yields than the literature method, but also avoids the use of large excesses of Br2, pyrophoric sBuLi, and column chromatography techniques for purification. In addition, this chapter introduces the synthesis of novel intramolecular derived ditert-butyldimethylxanthene and dimethylthioxanthene FLPs with wider P···B separations. In chapter 4, the preparation of novel species derived from an acridan backbone are discussed. This scaffold was used for the synthesis of a range of disubstituted phosphine (PNP) Lewis bases. The large steric bulk of tert-butyl, iso-propyl and mesityl substituents was shown to prevent clean disubstitution of the phosphine moiety onto the acridan backbone. Phenyl and para-tolyl substituents, by contrast, gave the desired disubstituted acridan derivatives, and these species have been characterised spectroscopically and crystallographically. The reactivity of these Lewis bases with the Lewis acid B(C6F5)3 has been investigated. Neither donor/acceptor coordination nor frustrated Lewis pair behaviour is observed; unexpected C-H activation of the N-Me group of the acridan backbone is proposed based on spectroscopic data, and the structural authentication of a related derivative. This represents the first example of FLP-mediated sp3 C-H bond activation. Additionally, the synthesis of a novel intramolecular acridan-derived FLP featuring -PPh2/-B(C6F5)2 as the Lewis base/acid pair has been successfully achieved. This acridan FLP features a P···B separation (4.451(9) Å), which is slightly wider that the analogous dimethylxanthene FLP. Interestingly, it reacts with H2 at room temperature in a manner utilizing the proximal N-CH3 moiety as the Lewis base instead of the PPh2 group. This result led to related synthesis and reactivity studies of the bis-borane Lewis acid (BNB) featuring two pendant B(C6F5)2 groups, which also reacts with H2 at room temperature (1 atm) in similar fashion utilizing B/N cooperativity. Furthermore, this compound also shows unusual C-N bond activation behaviour accompanying the uptake of CO2 and CO in the presence of tBu3P. Chapter 5 reports on further investigations into the reactivity of previously reported dimethylxanthene-based phosphine/borane FLPs towards alkynes. The –PPh2 and –PMes2 containing systems (featuring B(C6F5)2 as Lewis acid component) were found to C-H activate the terminal alkyne PhCCH; the weaker -PPh2 donor system was found to give rise to an equilibrium mixture of the free FLP and phosphonium acetylide in CD2Cl2 solution at room temperature. This system was also found to react with the B-H bonds of HBpin and HBcat via C-B/B-H metathesis reactions that lead to the replacement of the -B(C6F5)2 moiety by -Bpin/-Bcat, with accompanying transfer of HB(C6F5)2 to the phosphine Lewis base. This transformation underpins the ability of this system to act as a pre-catalyst for the hydroboration of terminal (PhCCH) and internal alkynes (PhCCPh and PhCCMe) with HBpin. The active species is derived from the HB(C6F5)2 fragment generated in the borane metathesis reaction. Chapter 6 presents further reactivity studies of dimethylxanthene FLPs featuring - PiPr2 and -PPh2 Lewis bases (with -B(C6F5)2 as the Lewis acid) in the activation of Si-H and Sn-H bonds. It was found that the more strongly Lewis basic -PiPr2 FLP could activate the Si-H bonds in PhSiH3, Ph2SiH2 and SiH4; further reaction leads to Si/B metathesis yielding ‘migrated’ species in a similar fashion to that occurring with HBpin and HBcat. The more weakly Lewis basic -PPh2 FLP however, was found to be unreactive towards Ph2SiH2, Et3SiH and Ph3SiH, while the reaction with PhSiH3 leads to the formation of a similar ‘migrated’ species. The -PiPr2-containing FLP was also found to be reactive towards heavier group 14 hydrides, activating the Sn-H bonds of nBu3SnH and Ph3SnH to form zwitterionic phosphonium stannylium hydrides.

This thesis reports the reactivity of zirconocene hydrazides, imides and silylamides, as well as the reactivity of titanium permethylpentalene complexes. Particular focus is paid to the reactions of hydrazides and imides with boranes and silanes, and reactions of silylamides with terminal alkynes, boranes and silanes.

This thesis discusses the development of novel titanium-containing layered double hydroxides (Ti-LDHs) as semiconductor photocatalysts for the photo-oxidation of simple organic molecules. LDHs are introduced in Chapter 1 as compositionally flexible anionic clays, whose layered structure and tuneable properties make them highly interesting in a wide range of applications, including environmental purification, drug delivery and photocatalysis. In the latter case, LDHs have been used primarily in the photocatalytic degradation of organic pollutants, photo-reduction of CO2 and photocatalytic water splitting. Only limited research has been done into the controlled organic molecule photo-oxidation, where the oxidation is stopped at an intermediate stage rather than proceeding all the way to degradation products. Chapter 2 outlines the five different synthetic methods for Ti-LDH preparation and their viability in the synthesis of pure NiTi- and MgAlTi-LDHs with different Ni:Ti and Al:Ti ratios, respectively. The crystallinity, morphology, structure, composition and band gap energies of the Ti-LDHs were analysed, so as to determine the effect of the synthetic conditions and Ti content on their properties. Furthermore, the highly crystalline urea hydrothermal MgAlTi-LDH samples were characterised by high-angle annular dark-field imaging (HAADF) as well as by 1H, 27Al and 47/49Ti solid state NMR spectroscopy. In Chapter 3, the activity of the Ti-LDHs in the photo-oxidation of diphenylmethanol is studied, and compared to that of anatase TiO2 as a benchmark photocatalyst. The importance of short-wavelength radiation is discussed, especially for control experiments in the absence of a catalyst. The effects of the synthetic method, Ti content, catalyst and reactant loading, and irradiation time were examined for selected Ti-LDHs. Chapter 4 extends the study of the photocatalytic properties of Ti-LDHs beyond diphenylmethanol photo-oxidation to also include benzyl alcohol, cyclooctanol and benzylamine. This allows the determination of whether Ti-LDHs can be used to photo-oxidise a wider range of functional groups as part of either aromatic or aliphatic systems. Lastly, Chapter 5 details the synthesis and characterisation of TiO2@Ti-LDH core-shell hybrid materials, and looks at their application in the photo-oxidation of diphenylmethanol. The conversion using the core-shell photocatalysts was compared to that obtained with a mechanical mixture of TiO2 and Ti-LDHs, in order to study any synergistic heterojunction effects.

Producción Científica, New 1,2-azolylamidino complexes cis-[Ru(bipy)2(NH═C(R)az*-κ2N,N)](OTf)2 (R = Me, Ph; az* = pz, indz, dmpz) are synthesized via chloride abstraction after a subsequent base-catalyzed coupling of a nitrile with the previously coordinated 1,2-azole. The synthetic procedure allows the easy obtainment of complexes having different electronic and steric 1,2-azoylamidino ligands. All of the compounds have been characterized by 1H, 13C, and 15N NMR and IR spectroscopy and by monocrystal X-ray diffraction. Photophysical studies support their phosphorescence, whereas their electrochemistry reveals reversible RuII/RuIII oxidations between +1.13 and +1.25 V (vs SCE). The complexes have been successfully used as catalysts in the photooxidation of different thioethers, the complex cis-[Ru(bipy)2(NH═C(Me)dmpz-κ2N,N)]2+ showing better catalytic performance in comparison to that of [Ru(bipy)3]2+. Moreover, the significant catalytic performance of the dimethylpyrazolylamidino complex is applied to the preparation of the drug modafinil, which is obtained using ambient oxygen as an oxidant. Finally, mechanistic assays suggest that the oxidation reaction follows a photoredox route via oxygen radical anion formation., Ministerio de Economía, Industria y Competitividad (grants PGC2018- 099470-B-I00 and RTI2018-095038-B-I00), Junta de Castilla y León (grant VA130618), Junta de Castilla y León - Fondo Social Europeo (project BU263P18)

Semiconductor nanocrystals, or quantum dots, have attracted significant interest for use in solid state lighting, biological imaging, photovoltaics, catalysis, and displays such as televisions or tablets. Quantum dots excel in these applications because of their narrow emission profiles, high absorptivity at high energies, and optoelectronic properties that can be easily tuned using colloidal chemistry. The last point in particular has driven the development of new synthetic methods for producing a range of semiconducting materials on the nanoscale. Academically, interest in the synthesis of quantum dots has also extended to the mechanism of their formation and its implications for the growth of nanoscale crystals more generally. This thesis addresses facets of both points above, first by developing several novel syntheses for indium and gallium phosphide nanocrystals, and second by leveraging the synthetic control it allows to study the mechanisms of homogeneous crystal growth. Chapter 1 provides a brief overview of the colloidal syntheses, optoelectronic properties, and formation mechanisms of quantum dots. Emphasis is placed on the development of new chemical syntheses for nanoscale materials and how the size, size distribution, and morphology can be carefully controlled by thoughtful reaction design. The progression of quantum dot synthesis is presented and specific innovations to the precursor and surfactant design are highlighted. Next, a brief discussion about nanocrystal surface chemistry and its impact on the photophysical properties of the inorganic core is described along with its proposed influence on the kinetics of nanocrystal growth. Finally, classical theories of homogeneous crystal growth are presented and used to explain the origin of the exceptionally narrow size distributions accessible in a wide range of materials. Chapter 2 introduces two novel synthetic pathways to InP nanocrystals. The first describes a small library of substituted aminophosphines that can control the precursor conversion reactivity by over an order of magnitude. Leveraging the collection of aminophosphines, it is demonstrated that at sufficiently high temperatures, the rate of precursor conversion can be used to vary the final nanocrystal size—disputing previous findings for InP nanocrystals. We show that the reactivity of the phosphine is governed by a pre-equilibrium between the precursor and an intermediate (P(NHR)3) that goes on to form InP. Variations to the initial aminophosphine substitution pattern change the position of the pre-equilibrium, thereby allowing the rate of [InP]i deposition to be controlled. The second synthetic method leverages metal phosphonate salts as a surfactant to synthesize large samples of InP. We find that the nanocrystals grow via a ripening mechanism and display excellent crystallinity as determined by powder X-ray diffraction and pair distribution function analysis. Finally, we demonstrate that the final nanocrystals are bound by both phosphonates and phosphines through the use of 31P nuclear magnetic resonance spectroscopy. Chapter 3 expands on the syntheses of InP in the previous chapter by developing methods to form GaP, InxGa1-xP, and InP-based core-shell structures. At the onset, two distinct syntheses of GaP are introduced, one similar to the metal phosphonate route used to form InP, and one that used a mixture of amines to stabilize GaP colloidally. The phosphonate method results in small GaP with somewhat indistinct scattering patterns, while the amine method results in large GaP whose morphology can be varied depending on the solvent selected. Leveraging the newly developed InP and GaP syntheses we demonstrate that InxGa1-xP alloys could be directly synthesized from mixtures of In3+ and Ga3+ salts. We also show that InxGa1-xP can be accessed indirectly via cation exchange of Zn3P2 or Cd3P2, however attempts at synthesizing alloys via cation exchange with phosphonate bound GaP were found to be largely unsuccessful. Finally, the chapter contains initial attempts at synthesizing GaP/InP core-shells with the intention of producing GaP/InP/GaP spherical quantum well architectures. Preliminary data show that InP can be deposited using several different methods, though it remains unclear whether the optical properties will be suitable for integration in solid state lighting applications. Chapter 4 examines the crystal growth processes that precede the formation of monodisperse ensembles of InP, PbS, and PbSe nanocrystals. Surprisingly, we find that nucleation persists for a substantial portion of the total reaction time—a stark departure from the canonical “burst” of nucleation proposed originally by Victor LaMer. We go on to measure the nucleation period for a variety of different reaction conditions and find that the fraction of reaction time nucleation extends over is sensitive to both the material and reaction temperature. This is consistent with a mechanism where faster kinetics of monomer attachment reduce the duration of crystal nucleation—a conclusion that can be surmised by nucleation mass balance models that show a clear material and temperature dependence on the rate of nanocrystal growth. We also interrogate the claim that solute molecules accumulate prior to the formation of mature nanostructures. In situ X-ray experiments clearly corroborate the appearance of solute-like species at early reaction times that build up prior to the appearance of crystals with extended structure. Finally, we propose a novel size-focusing mechanism predicated on a size dependent growth rate. Using population mass balance modeling we show that the measurements of size and size distribution are qualitatively consistent with a growth rate inversely proportional to nanocrystal size.

Colloidal semiconductor nanocrystals exist at the interface of inorganic chemistry, solid-state physics, and materials applications. The highly tunable and size-dependent properties position them as prime candidates for advancing a range of technologies, including improving efficiency in solid-state lighting devices and high color-purity displays. To be successful in these endeavors, quantum dots require excellent optical properties, such as bright emission. Optimization of a zinc sulfide coating is widely regarded as a key requirement to achieving these necessary performances. Even so, zinc sulfide nanocrystal chemistry remains underdeveloped. This dissertation addresses these shortcomings and provides comprehensive synthetic and analytical tools to harness the potential of zinc sulfide containing nanocrystals. Chapter 1 introduces semiconductor nanocrystals, also referred to as quantum dots, and begins with a description of the size-dependent optical properties. Factors that lead to poorer emission properties, such as undercoordinated surface atoms are discussed. Methods to alleviate these issues, including controlling the surface coordination environment, and design and growth of heterostructures are introduced. Lastly, synthetic approaches and nanocrystal formation mechanisms are described. Chapter 2 covers the synthesis and size-dependent optical properties of zinc sulfide nanocrystals. We find that commonly used solvents in nanocrystal reactions lead to the formation of polymeric byproducts that are challenging to purify away, and thus design the zinc sulfide synthesis such that these can be avoided. Leveraging a library of rate tunable thioureas the final nanocrystal size can be carefully controlled. The reactions follow a thermally activated growth process, with larger zinc sulfide nanocrystals accessible at higher temperatures. Most relevantly for later chapters, the surface coordination environment is highly important; bulkier zinc carboxylate ligands that cannot achieve high surface coverages result in higher growth rates. These results represent the most tunable size controls reported for zinc sulfide nanocrystals. Chapter 3 uses high resolution electron microscopy techniques to study the shape (morphology) of zinc sulfide nanocrystals, synthesized using the methods developed in the second chapter. Irregular, anisotropic growth is commonly seen in zinc sulfide shell growth and is attributed to core/shell interfacial strain. We find that this growth also occurs in the binary zinc sulfide system. Synthetic conditions favoring fast growth result in unselective, isotropic growth of spherical zinc sulfide. Conversely, slower conditions can lead to irregular, anisotropic shapes. The shape is also highly dependent on the coordination environment during growth. Small, sterically unencumbered ligands stabilize specific crystal facets, leading to selective, anisotropic growth. These findings are translated to shelling procedures in Chapter 6, and further emphasize the need to understand and characterize zinc sulfide surfaces. Chapter 4 establishes an empirical relationship between the band gap energy of a zinc sulfide nanocrystal and its diameter. The literature reports a wide spread of diameters for a given energy, meaning zinc sulfide sizes could not previously be easily calculated from their optical properties. Leveraging the size- and shape-control discussed in Chapters 2 and 3, we assess the utility of a range of nanocrystal characterization techniques for accurately sizing quantum confined zinc sulfide. Using electron microscopy and X-ray scattering methods we present an updated energy-size (“sizing curve”) relationship for zinc sulfide. These results represent the most comprehensive zinc sulfide nanocrystal sizing study and enable the rapid size characterization of zinc sulfide from its absorbance spectrum. This provided crucial insight into the reaction progressions described in Chapter 2. Chapter 5 covers our endeavors to characterize and quantify the zinc sulfide nanocrystal surface chemistry, which we believe is imperative to improving shelling procedures and optical properties in zinc sulfide heterostructures. With no published extinction coefficient, the surface coverages of zinc sulfide cannot be obtained. Using the size- and shape-controlled syntheses, in conjunction with optical absorption spectroscopy and elemental analysis, we calculate extinction coefficients for a range of zinc sulfide nanocrystal sizes. The size-dependence is well described by a power law, and this represents the first reported extinction coefficient for zinc sulfide. Using this, we report the first surface coverages of zinc sulfide nanocrystals and assess the binding affinity of zinc carboxylates to the surface by monitoring their displacement by L-type ligands. Chapter 6 widens the zinc sulfide synthetic methods developed in earlier chapters to deposit zinc sulfide shells onto blue-emitting II-VI and red-emitting III-V nanocrystals. The reaction shows versatility, shelling nanocrystals over a wide range of temperatures. We demonstrate morphology control over the zinc shell by altering the deposition kinetics and coordination environment. Usually, thick, homogenous shells are desired by the nanocrystal field. However, by correlating the shell morphology to its optical properties, we see that the anisotropic shells generally achieve higher photoluminescence quantum yields (PLQYs). We also report progress towards cadmium-free quantum dot downconverters for use in solid-state lighting applications. Among other things, the photoluminescence intensity evolution throughout the shelling procedure is highly dependent on the initial surface termination of the nanocrystal core. Application of surface treatments allows brighter zinc sulfide shelled III-V heterostructures to be accessed.

The evolution of electronics has become the staple thrust of modern scientific innovation: a need for advancing materials engineered for our equally rapidly advancing needs and computing requirements has fueled recent wealth of new materials. Here, I use the ideals of exotic materials design to answer this need, specifically for 2D materials. Two-dimensional (2D) van der Waals materials with in-plane anisotropy are of great interest for directional transport of charge and energy. I perform solid state synthesis to produce several such materials: an intrinsic antiferromagnet, superatomic semiconductors, and a polytype system with a component that displays the possibilities of Weyl nodes.The former, chromium sulfur bromide (CrSBr), is first synthesized, then fully studied structurally, compositionally, electronically, and magnetically. Second harmonic generation (SHG), more advanced than older techniques such as magneto-optical Kerr spectroscopy or Raman spectroscopy, allows us to fully understand the magnetic symmetry in this system as an interlayer antiferromagnetic and intralayer ferromagnetic in-plane anisotropic material. I also introduce published work in which we integrate CrSBr into different devices to show the utility of this fundamental research into a more practical application setting. It is used to stimulate more magnetic response from graphene — promising ultra-thin magnetic memory or sensory devices in future projects. Applying strain and external magnetic fields provides another tuning knob through which to access different functional modalities. In the latter third of this dissertation, we report a layered van der Waals semiconductor with in-plane anisotropy built upon the superatomic units of Mo₆S₃Br₆ (MSB), a robust construction with a direct gap of 1.64 eV. Next, MSB and Re₆Se₈Cl₂, another analogous superatomic vdW material, are potential candidates for optoelectronic applications; we qualify this by studying their Auger dynamics as a measure of quantum efficiency. Finally, layered van der Waals (vdW) materials belonging to the MM’Te₄ structure class have recently received intense attention due to their ability to host exotic electronic transport phenomena, such as in-plane transport anisotropy, Weyl nodes, and superconductivity. In summary, we have discovered two ternary exfoliatable vdW TMD polytypes with the composition TaFeTe₄, one of which (ꞵ) shows the prerequisite symmetry elements to be a type-II Weyl semimetal. This dissertation is a treatise to solid state synthesis, exploration into the more exotic spectrum of 2D materials, and robust and eclectic methods used to paint a full picture of different magnetic and electronic systems within.