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A new biomimetic model complex of the active site of acireductone dioxygenase (ARD) was synthesized and crystallographically characterized ( [Ni( ii )( N -(ethyl- N 'Me 2 )(Py)(2- t -ButPhOH))(OTf)]- 1). 1 displays carbon-carbon oxidative cleavage activity in the presence of O 2 towards the substrate 2-hydroxyacetophenone. This reactivity was monitored via UV-Visible and NMR spectroscopy. We postulate that the reactivity of 1 with O 2 leads to the formation of a putative Ni(III)-superoxo transient species resulting from the direct activation of O 2 via the nickel center during the oxidative reaction. This proposed intermediate and reaction mechanism were studied in detail using DFT calculations. 1 and its substrate bound derivatives display reactivity toward mild outer sphere oxidants, suggesting ease of access to high valent Ni coordination complexes, consistent with our calculations. If confirmed, the direct activation of O 2 at a nickel center could have implications for the mechanism of action of ARD and other nickel-based dioxygenases and their respective non-traditional, enzymatic moonlighting functions, as well as contribute to a general understanding of direct oxidation of nickel(II) coordination complexes by O 2 .

We report the reactivity, structures and spectroscopic characterization of reactions of phosphine-based ligands (mono-, di- and tri-dentate) with iron-carbide carbonyl clusters. Historically, the archetype of this cluster class, namely [Fe 6 (μ 6 -C)(μ 2 -CO) 4 (CO) 12 ] 2- , can be prepared on a gram-scale but is resistant to simple ligand substitution reactions. This limitation has precluded the relevance of iron-carbide clusters relating to organometallics, catalysis and the nitrogenase active site cluster. Herein, we aimed to derive a simple and reliable method to accomplish CO → L (where L = phosphine or other general ligands) substitution reactions without harsh reagents or multi-step synthetic strategies. Ultimately, our goal was ligand-based chelation of an Fe n (μ n -C) core to achieve more synthetic control over multi-iron-carbide motifs relevant to the nitrogenase active site. We report that the key intermediate is the PSEPT-non-conforming cluster [Fe 6 (μ 6 -C)(CO) 16 ] (2: 84 electrons), which can be generated in situ by the outer-sphere oxidation of [Fe 6 (μ 6 -C)(CO) 16 ] 2- (1: closo , 86 electrons) with 2 equiv. of [Fc]PF 6 . The reaction of 2 with excess PPh 3 generates a singly substituted neutral cluster [Fe 5 (μ 5 -C)(CO) 14 PPh 3 ] (4), similar to the reported reactivity of the substitutionally active cluster [Fe 5 (μ 5 -C)(CO) 15 ] with monodentate phosphines (Cooke & Mays, 1990). In contrast, the reaction of 2 with flexible, bidentate phosphines (DPPE and DPPP) generates a wide range of unisolable products. However, the rigid bidentate phosphine bis(diphenylphosphino)benzene (bdpb) disproportionates the cluster into non-ligated Fe 3 -carbide anions paired with a bdpb-supported Fe(ii) cation, which co-crystallize in [Fe 3 (μ 3 -CH)(μ 3 -CO)(CO) 9 ] 2 [Fe(MeCN) 2 (bdpb) 2 ] (6). A successful reaction of 2 with the tripodal ligand Triphos generates the first multi-iron-chelated, authentic carbide cluster of the formula [Fe 4 (μ 4 -C)(κ3-Triphos)(CO) 10 ] (9). DFT analysis of the key (oxidized) intermediate 2 suggests that its (μ 6 -C)Fe 6 framework remains fully intact but is distorted into an axially compressed, 'ruffled' octahedron distinct from the parent closo cluster 1. Oxidation of the cluster in non-coordinating solvent allows for the isolation and crystallization of the CO-saturated, intact closo -analogue [Fe 6 (μ 6 -C)(CO) 17 ] (3), indicating that the intact (μ 6 -C)Fe 6 motif is retained during initial oxidation with [Fc]PF 6 . Overall, we demonstrate that redox modulation beneficially 'bends' Wade-Mingo's rules via the generation of electron-starved (non-PSEPT) intermediates, which are the key intermediates in promoting facile CO → L substitution reactions in iron-carbide-carbonyl clusters., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

The reaction between Th(IV) dipyriamethyrin dichloride and sodium cyclopentadienyl (Cp) results in the formation of a cyclopentadienyl capped thorium dipyriamethyrin complex, which to our knowledge represents the first expanded porphyrin f-element Cp complex.

A heteroleptic copper(I) bis(phenanthroline) complex with aldehyde groups at the 4,7 positions of the phenanthroline ligand was synthesized. The complex is responsive to alcohol, resulting in a distinct colour change caused by the facile reaction of the aldehyde group with alcohol, forming a hemiacetal product. The aldehyde species can be regenerated after heating the intermediate at 80 °C for 10 minutes, demonstrating the reusability of the complex for alcohol detection. This work presents a new strategy for applying transition metal complexes in small molecule sensing by installing functional groups in the secondary coordination sphere which reversibly react with analytes.

Developing efficient photocatalysts that perform multi electron redox reactions is critical to achieving solar energy conversion. One can reach this goal by developing systems which mimic natural photosynthesis and exploit strategies such as proton-coupled electron transfer (PCET) to achieve photochemical charge accumulation. We report herein a heteroleptic Cu(i)bis(phenanthroline) complex, Cu-AnQ, featuring a fused phenazine-anthraquinone moiety that photochemically accumulates two electrons in the anthraquinone unit via PCET. Full spectroscopic and electrochemical analyses allowed us to identify the reduced species and revealed that up to three electrons can be accumulated in the phenazine-anthraquinone ring system under electrochemical conditions. Continuous photolysis of Cu-AnQ in the presence of sacrificial electron donor produced doubly reduced monoprotonated photoproduct confirmed unambiguously by X-ray crystallography. Formation of this photoproduct indicates that a PCET process occurred during illumination and two electrons were accumulated in the system. The role of the heteroleptic Cu(i)bis(phenanthroline) moiety participating in the photochemical charge accumulation as a light absorber was evidenced by comparing the photolysis of Cu-AnQ and the free AnQ ligand with less reductive triethylamine as a sacrificial electron donor, in which photogenerated doubly reduced species was observed with Cu-AnQ, but not with the free ligand. The thermodynamic properties of Cu-AnQ were examined by DFT which mapped the probable reaction pathway for photochemical charge accumulation and the capacity for solar energy stored in the process. This study presents a unique system built on earth-abundant transition metal complex to store electrons, and tune the storage of solar energy by the degree of protonation of the electron acceptor., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

We report a copolymeric fluorescent sensor that is selective for lithium chloride. The two constituent polymers comprise pendent triphenylethylene (TPE) moieties for aggregate induced emission (AIE) along with either strapped-calix[4]pyrrole or secondary ammonium groups that drive aggregation via self-assembly upon polymer mixing. Addition of LiCl in acetonitrile disrupts the strapped-calix[4]pyrrole/secondary ammonium chloride salt host-guest crosslinks leading to disaggregation of the polymer chains and a decrease in TPE emission. The lack of AIE perturbation upon addition of NaCl, KCl, MgCl 2 or CaCl 2 provides for high selectivity for LiCl relative to potential interferants. This supramolecular dual polymer approach could serve as a complement to more traditional sensor systems., Competing Interests: The authors declare no conflict of interest., (This journal is © The Royal Society of Chemistry.)

A cyclo[2]carbazole[2]pyrrole (2) consisting of two carbazoles and two pyrroles has been synthesized by directly linking the carbazole 1- and 8-carbon atoms to the pyrrole α-carbon atoms. Macrocycle 2 is an extensively conjugated 16-membered macrocyclic ring that is fixed in a pseudo-1,3-alternate conformation. This provides a preorganized anion binding site consisting of two pyrrole subunits. 1 H NMR spectroscopic analysis revealed that only the two diagonally opposed pyrrole NH protons, as opposed to the carbazole protons, take part in anion binding. Nevertheless, cyclo[2]carbazole[2]pyrrole 2 binds representative anions with higher affinity in CD 2 Cl 2 than calix[4]pyrrole (1), a well-studied non-conjugated tetrapyrrole macrocycle that binds anions via four pyrrolic NH hydrogen bond interactions. On the basis of computational studies, the higher chloride anion affinity of receptor 2 relative to 1 is rationalized in terms of a larger binding energy and a lower host strain energy associated with anion complexation. In the presence of excess fluoride or bicarbonate anions, compound 2 loses two pyrrolic NH protons to produce a stable dianionic macrocycle [2-2H] 2- displaying a quenched fluorescence., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Palladium metallates containing 4-oxo-4 H -chromene-3-carbaldehyde derived ONS donor Schiff bases were synthesized and their efficacy was tested in the direct amination of diosgenin - a phyto steroid. Based on the pharmacological importance of diosgenin, the obtained derivatives were exposed to study their effect on breast cancer cells where they significantly reduced the growth of cancer cells and left non-malignant breast epithelial cells unaffected. Among the derivatives, D3, D4 and D6 showed a better anti-proliferative effect and further analysis revealed that the D3, D4 and D6 derivatives markedly promoted cell cycle arrest and apoptosis by attenuation of the AKT1 signalling pathway.

Inspired by the tetracationic "Texas-sized" molecular box, a neutral analogue containing four iodotriazole halogen bond-promoting subunits ("Ibox") was synthesized. This new macrocycle was prepared by means of azide-alkyne click chemistry. It was found to recognize Cl - , Br - and I - anions (as their tetrabutylammonium salts) in CDCl 3 . 1 H NMR spectroscopic titrations revealed a higher affinity for the heavier halide anions and provided support for a preferred 1 : 2 binding stoichiometry.

We report the synthesis and reactivity of a model of [Fe]-hydrogenase derived from an anthracene-based scaffold that includes the endogenous, organometallic acyl(methylene) donor. In comparison to other non-scaffolded acyl-containing complexes, the complex described herein retains molecularly well-defined chemistry upon addition of multiple equivalents of exogenous base. Clean deprotonation of the acyl(methylene) C-H bond with a phenolate base results in the formation of a dimeric motif that contains a new Fe-C(methine) bond resulting from coordination of the deprotonated methylene unit to an adjacent iron center. This effective second carbanion in the ligand framework was demonstrated to drive heterolytic H 2 activation across the Fe(ii) center. However, this process results in reductive elimination and liberation of the ligand to extrude a lower-valent Fe-carbonyl complex. Through a series of isotopic labelling experiments, structural characterization (XRD, XAS), and spectroscopic characterization (IR, NMR, EXAFS), a mechanistic pathway is presented for H 2 /hydride-induced loss of the organometallic acyl unit ( i.e. pyCH 2 -C[double bond, length as m-dash]O → pyCH 3 +C[triple bond, length as m-dash]O). The known reduced hydride species [HFe(CO) 4 ] - and [HFe 3 (CO) 11 ] - have been observed as products by 1 H/ 2 H NMR and IR spectroscopies, as well as independent syntheses of PNP[HFe(CO) 4 ]. The former species ( i.e. [HFe(CO) 4 ] - ) is deduced to be the actual hydride transfer agent in the hydride transfer reaction (nominally catalyzed by the title compound) to a biomimetic substrate ([ Tol Im](BAr F ) = fluorinated imidazolium as hydride acceptor). This work provides mechanistic insight into the reasons for lack of functional biomimetic behavior (hydride transfer) in acyl(methylene)pyridine based mimics of [Fe]-hydrogenase., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Recent decades have witnessed the emergence of Au(i) bis-N-heterocyclic carbenes (NHCs) as potential anticancer agents. However, these systems exhibit little interaction with serum proteins ( e.g. , human serum albumin), which presumably impacts their pharmacokinetic profile and tumor exposure. Anticancer drugs bound to human serum albumin (HSA) often benefit from significant advantages, including longer circulatory half-lives, tumor targeted delivery, and easier administration relative to the drug alone. In this work, we present Au(i) bis-NHCs complexes, 7 and 9 , capable of binding to HSA. Complex 7 contains a reactive maleimide moiety for covalent protein conjugation, whereas its congener 9 contains a naphthalimide fluorophore for non-covalent binding. A similar drug motif was used in both cases. Complexes 7 and 9 were prepared from a carboxylic acid functionalized Au(i) bis-NHC (complex 2 ) using a newly developed post-synthetic amide functionalization protocol that allows coupling to both aliphatic and aromatic amines. Analytical, and in vitro techniques were used to confirm protein binding, as well as cellular uptake and antiproliferative activity in A549 human lung cancer cells. The present findings highlight a hitherto unexplored approach to modifying Au(i) bis-NHC drug candidates for protein ligation and serve to showcase the relative benefits of covalent and non-covalent HSA binding., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Two-phenoxy walled calix[4]pyrroles 1 and 2 strapped with small rigid linkers containing pyridine and benzene, respectively, have been synthesized. 1 H NMR spectroscopic analyses carried out in CDCl 3 revealed that both of receptors 1 and 2 recognize only F - and HCO 3 - among various test anions with high preference for HCO 3 - (as the tetraethylammonium, TEA + salt) relative to F - (as the TBA + salt). The bound HCO 3 - anion was completely released out of the receptors upon the addition of F - (as the tetrabutylammonium, TBA + salt) as a result of significantly enhanced affinities and selectivities of the receptors for F - once converted to the TEAHCO 3 complexes. Consequently, relatively stable TEAF complexes of receptors 1 and 2 were formed via anion metathesis occurring within the receptor cavities. By contrast, the direct addition of TEAF to receptors 1 and 2 produces different complexation products initially, although eventually the same TEAF complexes are produced as via sequential TEAHCO 3 and TBAF addition. These findings are rationalized in terms of the formation of different ion pair complexes involving interactions both inside and outside of the core receptor framework., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

A post-synthetic strategy is reported that allows for functionalisation of Au(i)-bis NHCs via carbonate formation. The scope of this methodology was explored using both aromatic and aliphatic alcohols. As a demonstration of potential utility, the fluorescent Au(i)-bis NHC conjugate 5 was prepared; it was found to have enhanced stability when formulated with bovine serum albumin, localise within the mitochondria of A549 cells and do so without compromising the high cytotoxicity seen for the parent Au(i)-bis NHC system.

Calix[4]pyrrole (C4P)-based systems have been extensively explored as binding agents for anions and ion pairs. However, their capacity to act as molecular containers for neutral species remains underexplored. We report here the molecular recognition of pyrazine N , N '-dioxide ( PZDO ) using a series of aryl extended C4Ps including three α,α-diaryl substituted C4Ps (receptors 1-3 ), an α,β-diaryl substituted C4P (receptor 4 ) and an α,α,α,α-tetraaryl substituted C4P (receptor 5 ). Single crystal structural analyses of the 2 : 1 host-guest complexes between receptors 1-3 and PZDO revealed that the C4P subunits exist in an unusual partial cone conformation and that the PZDO guest is held within electron-rich cavities formed by the lower rims of the individual C4P macrocycle. In contrast, receptor 5 was seen to adopt the cone conformation in the solid state, allowing one PZDO molecule to be accommodated inside the upper-rim cavity. Evidence for guest-directed self-assembly is also seen in the solid state. Evidence for C4P- PZDO interactions in CD 3 CN/CD 3 OD solution came from 1 H NMR spectroscopic titrations. Electrostatic potential maps created by means of density functional theory calculations were constructed. Density functional theory calculations were also performed to analyse the energetics of various limiting binding modes. On the basis of these studies, it is inferred that interactions between the 'two-wall' C4P derivatives ( i.e. receptors 1-4 ) and PZDO involve a complex binding mode that differs from what has been seen in previous host-guest complexes formed between C4Ps and N -oxides. The present study thus paves the way for the further design of C4P-based receptors with novel recognition features., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

New Rh (1) and Ir (2) complexes of an N-heterocyclic carbene (NHC) featuring a terthiophene backbone were synthesized. Single crystal X-ray diffraction studies of 1 and 2 at 100 K and 298 K respectively, revealed two enantiotropic polymorphic phases with similar lattice parameters for each compound. The transition temperature between two crystalline forms for each compound was determined by measuring the percentage of reflections with a different space group ranging from 100 K to 298 K. Both 1 and 2 were also found to catalyze the hydrogen transfer reaction. The conducting metallopolymers poly-1 and poly-2 were synthesized from oxidative electropolymerization of 1 and 2, respectively, in CH 2 Cl 2 electrolyte solution on indium tin oxide-(ITO) coated glass. The electrochromic properties of synthesized conducting metallopolymers were studied by UV-vis-NIR spectroelectrochemistry.

Controlled partial decomposition of 2-selenonicotinic acid in the presence of Co2+ or Ni2+ resulted in the in situ formation of an unusual MOF based on triselenane ligands (RSeSeSeR) coordinated to M2+ centers as NSeN-pincers. Post-synthetic oxidation by treatment with aqueous H2O2 facilitates its solid-state conversion into a RSeO2- molecular coordination complex, which was tracked via powder X-ray diffraction studies and by single-crystal structural resolution of the final product.

β,β'-Phenylene bridged hexaphyrin[1.0.1.0.1.0] (naphthorosarin), an expanded porphyrin possessing C 3v -symmetry, has been shown to possess unique electronic features. We now report a bimetallic Rh(i)-complex of naphthorosarin retaining 24 π-antiaromatic characteristics. The two Rh(i) cations reside on opposite sides of the macrocyclic π-system and are separated at a distance consistent with a possible Rh(i)-Rh(i) metallic bond interaction.

Three tetranuclear (1-3) complexes and a mononuclear (4) palladium(ii) complex were synthesized from 3-acetyl-chromen-2-one Schiff base ligands [H 2 -3MAC-Rtsc] (where R = H [H 2 -3MAC-tsc]; CH 3 [H 2 -3MAC-mtsc]; C 2 H 5 [H 2 -3MAC-etsc] or C 6 H 5 [H 2 -3MAC-ptsc]) and potassium tetrachloropalladate. Their formation was confirmed by spectroscopic techniques and X-ray crystallographic analysis. Their ability to bind with DNA and albumin was analysed by using absorption and emission titrations. The MTT assay was carried out to analyze the anticancer potential of the ligands and synthesized complexes against HepG2 (human liver cancer) and HT-29 (human colon cancer) cells. In addition, the compounds were less toxic when tested against the human normal keratinocyte cells (HaCaT). Ligands and complexes displayed better cytotoxicity with lower IC 50 values than the standard drug cisplatin. Further AO-EB and DAPI staining assays were carried out to detect the mode of cell death induced by the complexes i.e. apoptosis or necrosis. The complex 3 showed better cytotoxicity and was further subjected to flow cytometric analysis. The results suggested that the complex 3 induced apoptotic cell death.

The synthesis and characterization of the alkylidenyl-dibenzihexaphyrins bearing four indanedionyl groups at the meso-positions linked via four meso-exocyclic double bonds is reported. Treatment with trifluoroacetic acid at 50 °C leads to C(α)-protonation of the two indanedionyl groups resulting increased macrocyclic conjugation with dramatic red shifted absorption spectra.

A new mixed hexaphyrin, pyrihexaphyrin (0.1.0.0.1.0) ( 1 ), was prepared via an acid catalyzed cyclization between 5,5'-(pyridine-2,6-diyl)bis(pyrrole-2-carbaldehyde) ( 2 ) and terpyrrole ( 3 ). This expanded porphyrin undergoes a ring contraction upon metallation with uranyl silylamide [UO 2 [N(SiMe 3 ) 2 ] 2 ] under anaerobic conditions followed by purification over basic aluminum oxide exposed to air. The uranyl-contracted pyrihexaphyrin (0.0.0.0.1.0) complex ( 4 ) produced as a result contains a unique structural architecture and possesses a formally 22 π-electron globally aromatic periphery, as inferred from NMR spectroscopy, single crystal X-ray diffraction, and computational analyses. Support for the proposed contraction mechanism came from experimental data and DFT calculations. Proton NMR and mass spectroscopic analysis provided the first insight into expanded porphyrin-mediated activation of the uranyl dication (UO 2 2+ ).

We demonstrate that bisulfite can be used for reduction of a highly electrophilic anthraquinone derivative, N,N'-dimethyl-2,6-diaza-9,10-anthraquinonediium (DAAQ), and subsequent autoxidation generates an equivalent of hydrogen peroxide. The mechanism for DAAQ reduction by bisulfite, DAAQ electrochemistry, and use of a simple test strip assay for H2O2, are described.

A set of self-assembled tri- and tetrapodal metal coordination cage structures (cage-1 and cage-2, respectively) constructed from the uranyl dication (UO22+) and a dibenzoic acid functionalised cis-calix[4]pyrrole (1) are described. The inherent photochemical reactivity of the uranyl dication mediates the transformation of cage-1 to cage-2via the activation of molecular oxygen.

Four new disubstituted and monosubstituted nitro- and amino- bis(pyrazol-1-yl)pyridine (bppy) ligands, substituted at the pyrazole 4-position (1, 2, 5, 6) have been synthesized, along with two luminescent Eu(iii) tris-β-diketonate derivatives of the amino substituted ligands (7, 8). The compounds have been studied using UV-Vis absorbance spectroscopy and cyclic voltammetry which has allowed for characterization of the electronic environments of these ligands. The calculated HOMO-LUMO gap values (1: 3.54 eV; 2: 3.53 eV; 5: 3.01 eV; 6: 3.66 eV) differ from that of bppy (3.86 eV) and the range is indicative that tuning of the ligand electronic environment is possible. Additionally, fluorescence spectroscopy studies were employed to determine ligand T 1 energy levels of the amine-bearing ligands 2 and 6, yielding values of T 1 of 25 381 cm -1 and 26 201 cm -1 , respectively. These ligands were employed in the synthesis of Eu(iii) complexes 7 and 8, for which the absolute and intrinsic quantum yields, lifetimes and ligand sensitization efficiencies were determined.

The reaction between non-aqueous uranyl silylamide (UO 2 [N(SiMe 3 ) 2 ] 2 ·2THF) under anaerobic conditions or uranyl acetate (UO 2 (OAc) 2 ·2H 2 O) under standard laboratory conditions and dipyriamethryin affords a bench-stable uranyl complex. Competition studies as well as DFT calculations provide support for the observed selectivity for the uranyl cation over trivalent lanthanide and multiple transition metal precursors.

The Bull-James boronic acid assembly is used simultaneously as a chiral auxiliary for kinetic resolution and as a chiral shift reagent for in situ enantiomeric excess (ee) determination by 1 H NMR spectroscopy. Chiral terminal alkyne-containing amines, and their corresponding chiral triazoles formed via CuAAC, were probed in situ. Selectivity factors of up to s = 4 were imparted and measured, accurate to within ±3% when compared to chiral GC.

A 3-dimensional networked molecular cage, , has been synthesized. This macrocycle-based framework was prepared from a solvothermal reaction involving a flexible organic building block, calix[4]pyrrole dibenzoic acid (H2), and Pr(NO3)3·6H2O. A unique feature of is that it retains free calix[4]pyrrole molecules in the framework pores. Treatment with a fluoride anion source serves to destroy the network and allows release of the organic guest. The net result is a 'molecular ship' in a 'breakable bottle'.

Three new tris(2-pyridylmethyl)amine-based ligands possessing phenylethynyl units have been prepared using Sonogashira couplings and substitution reactions. Copper(ii) complexes of those tetradentate ligands have also been synthesized. Solid-state structures of the six new compounds have been determined by single-crystal X-ray diffraction analyses. Examination of the molecular structures of the ligands revealed the expected triangular geometries with virtually undeformed carbon-carbon triple bonds. While the tertiary nitrogen of the free ligands seem to be prevented from participation in supramolecular non-covalent interactions by the pyridyl hydrogen at the 3-position, the pyridyl nitrogens play a crucial role in the packing mode of the crystal structure. The nitrogens form weak hydrogen bonds, varied in length between 2.32 and 2.66 Å, with the pyridyl hydrogen of its neighbouring molecule. The [NH-C] contacts enforce one-dimensional columnar assemblies on ligands that organize into wall-like structures, which in turn assemble into three-dimensional structures through CH-π interactions. Structural analyses of Cu(ii) complexes of the ligands revealed propeller-like structures caused by steric crowding of three pyridine ligands. The copper complexes of the ligands having three phenylethynyl substituents showed a remarkably deformed carbon-carbon triple bond enforced by a steric effect of the three phenyl groups. Most significantly, a total of seventy non-covalent interactions, classified into twelve types of hydrogen-involving short contacts, were identified in this study. The phenylethynyl substituent participated in forty-two interactions as a hydrogen bond acceptor, and its role was more distinctive in the crystal structures of the Cu(ii) complexes.

New tetrakis - and hexakis (1 H -pyrrole-2-carbaldehyde) anion receptors are described. The anion binding properties of these receptors were studied in organic media and in the solid state. The receptors displayed good affinity for the dihydrogenphosphate and pyrophosphate anions (as the tetrabutylammonium salts) in chloroform even in the presence of a polar protic solvent, methanol. Solution phase spectroscopic analyses proved consistent with the binding mode seen in single crystal structural studies of the dihydrogenphosphate and pyrophosphate complexes and provided support for the contention that these receptors undergo conformational reorganization in order to accommodate the bound oxoanions both in chloroform solution and in the solid state.

Ferrocene containing N -heterocyclic carbene (NHC) ligated gold(I) complexes of the type [Au(NHC) 2 ] + were prepared and found to be capable of regulating the formation of reactive oxygen species (ROS) via multiple mechanisms. Single crystal X-ray analysis of bis(1-(ferrocenylmethyl)-3-mesitylimidazol-2-ylidene)-gold(I) chloride ( 5 ) and bis(1,3-di(ferrocenylmethyl)imidazol-2-ylidene)-gold(I) chloride ( 6 ) revealed a quasi-liner geometry around the gold(I) centers, (i.e., the C - Au - C bond angle were measured to be ~177° and all the Au - C carbene bonds distances were in the range of 2.00 (7) - 2.03 (1) Å). A series of cell studies indicated that cell proliferation inhibition and ROS generation were directly proportional to amount of ferrocene contained within the [Au(NHC) 2 ] + complexes (IC 50 of 6 < 5 < bis(1-benzyl-3-mesitylimidazol-2-ylidene)-gold(I) chloride ( 4 )). Complexes 4 - 6 were also confirmed to inhibit thioredoxin reductase as inferred from lipoate reduction assays and increase chelatable intracellular zinc concentrations. RNA microarray gene expression assays revealed that 6 induces endoplasmic reticulum stress response pathways as a result of ROS increase.

We report the preparation and characterization of films of electroactive supramolecular polymers based on non-electroactive oligoalanines and electroactive oligoanilines. Fibroblasts adhered to and proliferated on the films, and the delivery of the clinically relevant anti-inflammatory drug dexamethasone phosphate could be enhanced upon the application of an electrical stimulus.

Photoexcitation of dichloromethane solutions of an uranyl macrocyclic complex with cyclo[1]furan[1]pyridine[4]-pyrrole () at the near-infrared (NIR) band (1177 nm) in the presence of electron donors and acceptors resulted in NIR-induced electron transfer without producing singlet oxygen via energy transfer.

In order to understand the still-poorly understood interplay between calix[4]arene conformations and cation and anion recognition in multicomponent systems, the ion pair receptors 1 and 2 were synthesized. In solution and in the solid state, the calix[4]arene subunit of receptor 1 adopts a cone conformation, while that of 2 interconverts between the cone and the partial cone conformation. These geometric features differ from previous systems where the calix[4]arene moiety was locked in the 1,3-alternate conformation. A combination of 1 H NMR spectroscopic analyses and single crystal X-ray diffraction studies reveal that receptor 1 binds the fluoride and the chloride anion via significantly different binding modes, displaying, for instance, 1 : 1 and 2 : 3 binding stoichiometries with CsF and CsCl, respectively. In the case of 2 , the conformation of the calix[4]arene constituent of 2 is highly dependent on the size and quantity of anions present. For example, upon treatment of 2 with the fluoride anion (as both the TBA + and Cs + salts), the calix[4]arene unit coexists as cone and partial cone conformers that are inter-convertible. In the presence of excess CsF, the aromatic rings of the calix[4]arene subunit becomes locked in the pinched cone conformation with the result that an ion pair-mediated coordination polymer is formed. In the presence of excess CsCl, the calix[4]arene unit of 2 adopts only the partial cone conformation stabilized by aryl CH-anion hydrogen bonding interactions. The present systems constitute a rare set of related receptors wherein the effects of conformational changes are so tightly coupled with ion recognition.

A series of tetrakis(1H-pyrrole-2-carbaldehyde) receptors (2, 4, and 6) were synthesized in two steps from commercially available starting materials. The anion binding properties of these receptors can be tuned through electronic switching to stabilize a conformation displaying high affinity for the dihydrogenphosphate and pyrophosphate anions (as the tetrabutylammonium salts) in chloroform.

Using a tetrathiafulvalene functionalised calix[4]pyrrole (TTF-C[4]P; ) and alkyl diester-linked bis-dinitrophenols (), it was found that the solvent polarity and linker length have an effect on the molecular aggregation behaviour. 2D (1)H NOESY, DOSY NMR and UV-vis-NIR spectroscopic studies, as well as single crystal X-ray diffraction analyses support these conclusions.

An o-phenylenevinylene-bridged tetrapyrrolic macrocycle (2) was synthesized by means of a Horner-Wadsworth-Emmons reaction between benzylbisphosphonate and SEM-protected diformylpyrrole, followed by deprotection of the SEM groups. This conformationally flexible tetrapyrrole can be considered as an expanded calix[4]pyrrole analogue, which acts as a receptor for the chloride and bromide anions in THF-d8, but undergoes deprotonation upon exposure to the fluoride anion.

Tetrathiafulvalenes (TTF)-annulated [28]hexaphyrin affords an electron rich flexible π-conjugated system whose limiting conformations can be controlled through choice of solvents. The conformation-dependent intramolecular charge transfer character, as well as electron reserve capability of the hexakis-TTF annulated hexaphyrin, was analyzed.

A redox-switchable ligand, N,N'-dimethyldiaminocarbene[3]ferrocenophane (5), was synthesized and incorporated into a series of Ir- and Ru-based complexes. Electrochemical and spectroscopic analyses of (5)Ir(CO)2Cl (15) revealed that 5 displayed a Tolman electronic parameter value of 2050 cm(-1) in the neutral state and 2061 cm(-1) upon oxidation. Moreover, inspection of X-ray crystallography data recorded for (5)Ir(cis,cis-1,5-cyclooctadiene)Cl (13) revealed that 5 was sterically less bulky (%V(Bur) = 28.4) than other known diaminocarbene[3]ferrocenophanes, which facilitated the synthesis of (5)(PPh3)Cl2Ru(3-phenylindenylid-1-ene) (18). Complex 18 exhibited quasi-reversible electrochemical processes at 0.79 and 0.98 V relative to SCE, which were assigned to the Fe and Ru centers in the complex, respectively, based on UV-vis and electron pair resonance spectroscopic measurements. Adding 2,3-dichloro-5,6-dicyanoquinone over the course of a ring-opening metathesis polymerization of cis,cis-1,5-cyclooctadiene catalyzed by 18 ([monomer]0/[18]0 = 2500) reduced the corresponding rate constant of the reaction by over an order of magnitude (pre-oxidation: k(obs) = 0.045 s(-1); post-oxidation: k(obs) = 0.0012 s(-1)). Subsequent reduction of the oxidized species using decamethylferrocene restored catalytic activity (post-reduction: k(obs) = up to 0.016 s(-1), depending on when the reductant was added). The difference in the polymerization rates was attributed to the relative donating ability of the redox-active ligand (i.e., strongly donating 5 versus weakly donating 5(+)) which ultimately governed the activity displayed by the corresponding catalyst.

A set of metal-organic rotaxane frameworks (MORFs) are constructed with the use of a tetraimidazolium macrocycle, the terephthalate dianion, and the trivalent lanthanide metal cations Nd(III), Sm(III), Eu(III) or Tb(III) and are reported herein. The specific choice of the metal cation allows for control of the structure and luminescent properties of the resulting molecular frameworks.

The structure, stability, gas sorption properties and luminescence behaviour of a new lanthanide-phosphine oxide coordination material are reported. The polymer PCM-15 is based on Tb(III) and tris(p-carboxylated) triphenylphosphine oxide and has a 5,5-connected net topology. It exhibits an infinite three-dimensional structure that incorporates an open, two-dimensional pore structure. The material is thermally robust and remains crystalline under high vacuum at 150 °C. When desolvated, the solid has a CO(2) BET surface area of 1187 m(2) g(-1) and shows the highest reported uptake of both O(2) and H(2) at 77 K and 1 bar for a lanthanide-based coordination polymer. Isolated Tb(III) centres in the as-synthesized polymer exhibit moderate photoluminescence. However, upon removal of coordinated OH(2) ligands, the luminescence intensity was found to approximately double; this process was reversible. Thus, the Tb(III) centre was used as a probe to detect directly the desolvation and resolvation of the polymer.

PCM-14 is a dense coordination polymer formed from Ca(II) and an unusual organophosphonium ligand. The dehydrated framework contains 3-coordinate Ca(II) sites within catenated, chiral 3,3-connected nets. PCM-14 exhibits a stark CO(2) sorption selectivity over H(2), N(2) and O(2). The maximum CO(2) uptake was shown to be highly sensitive to the material pretreatment evacuation temperature.

The hybrid calix[2]phenol[2]pyrrole 4 and the fused pyrrolidine-containing macrocycle 9 were synthesized from two different isomeric starting materials, namely dimethyl 2-hydroxyisophthalate and 5-hydroxyisophthalate, respectively. The fused species 9 is devoid of obvious substrate binding properties. In contrast, the heterocalix system 4 displays the fluoride-induced conformational changes characteristic of the parent system., (This journal is © The Royal Society of Chemistry 2012)

A facile, one-pot synthesis of rotaxanated supramolecular organic frameworks (RSOFs) is reported. These systems consist of bis-carboxylate anions threaded through the core of tetraimidazolium macrocycles. Trivalent metal cations, yttrium(III) and smaller lanthanides, are used to "lock" the threaded strut in place. This results in the formation of three-dimensional RSOFs.

Two new expanded porphyrins, naphthorubyrin and naphthosapphyrin, were synthesized. The π-extended rubyrin was isolated and structurally characterized in its monoprotonated form. The sapphyrin congener undergoes pyrrole inversion as a function of the protonation state. These conformational effects are reflected in the spectroscopic features, including the excited singlet state lifetimes., (This journal is © The Royal Society of Chemistry 2011)

A three-dimensional extended, metal-organic rotaxane framework (MORF) that incorporates encircled "struts" has been synthesized through a one-pot self-assembly process involving a macrocyclic tetraimidazolium "molecular box", naphthalene dicaboxylate dianion, and Zn(II) cations. The present system represents progress towards controlling the features of three-dimensional metal-organic frameworks.

Lead(II)-texaphyrins and the first discrete binuclear μ-oxo bismuth(III)-texaphyrin are reported. The latter was characterized via single crystal X-ray diffraction analysis. Cell proliferation assays using the A2780 ovarian cancer cell line were used to determine the cytotoxicity of the complexes.

Diiridum complexes containing 1,1'-bis(N-benzimidazolylidene)ferrocene, a novel ditopic ligand comprised of two N-heterocyclic carbenes (NHCs) linked directly via their N-substituents to each cyclopentadienyl ring of a ferrocene moiety, were synthesized. Crystallographic analyses of these C(2)-symmetric bimetallic complexes revealed the benzimidazolylidene moieties were intramolecularly stacked in nearly opposing orientations, effectively forming Janus-type bis(NHC) structures in the solid state. Using a variety of electrochemical techniques, the oxidation potentials of the ferrocenyl groups in these complexes were found to depend on the auxillary ligands coordinated to the Ir centers (i.e., 1,5-cyclooctadiene vs. carbonyl). Similarly, the nu(CO) of carbonyls ligated to the Ir centers varied in accord with the oxidation state of the ferrocene contained with the bis(NHC) ligand. These results suggest that the Ir and Fe centers in these complexes are electronically coupled and that the electron donating ability of the bis(NHC) ligand reported herein can be tuned electrochemically.

The use of a pyrrole-strapped calix[4]pyrrole () permits the determination of chloride anion concentrations in mixed aqueous DMSO-d(6)-H(2)O environments via proton NMR spectroscopy.

The synthesis of binuclear organometallic ruthenium complexes of an expanded porphyrin-type macrocycle is reported; pyrrolic hydrogen bonding donors were found to interact with ancillary ligands in the primary coordination sphere and to stabilize coordinated dioxygen in an eta(2)-fashion.

The synthesis of an isoamethyrin derivative containing two CH(2)CH(2)CO(2)CH(3) moieties in the beta-pyrrolic positions and its use in the colorimetric detection of the uranyl cation after immobilization onto a solid support is reported.