16 results on '"Malaspina, Lorraine A."'
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2. Lewis Superacidic Divalent Bis( m ‐terphenyl)element Cations [(2,6‐Mes 2 C 6 H 3 ) 2 E] + of Group 13 Revisited and Extended (E=B, Al, Ga, In, Tl)
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Duvinage, Daniel, Malaspina, Lorraine A., Grabowsky, Simon, Mebs, Stefan, and Beckmann, Jens
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540 Chemistry ,570 Life sciences ,biology ,000 Computer science, knowledge & systems - Abstract
In a combined experimental and computational study, the molecular and electronic structures of the divalent bis(m- terphenyl)element cations [(2,6-Mes2C6H3)2E]+ of group 13 (1, E=B; 2, E=Al; 3, E=Ga; 4, E=In; 5, E=Tl) were investigated. The preparation and characterization of 2, 3 and 5 were previously reported by Wehmschulte’s (Organometallics 2004, 23, 1965– 1967; J. Am. Chem. Soc. 2003, 125, 1470–1471) and our groups (Organometallics 2009, 28, 6893–6901). The indinium ion 4 was prepared and fully characterized for the first time. Attempts to prepare the borinium ion 1 by fluoride or hydride abstraction were unsuccessful. The electronic structures of 1–5 and the stabilization by the bulky m-terphenyl substituents were analyzed using quantum chemical calculations and compared to the divalent bis(m-terphenyl)pnictogenium ions [(2,6- Mes2C6H3)2E]+ of group 15 (6, E=P; 7, E=As; 8, E=Sb; 9, E=Bi) previously investigated by our group (Angew. Chem. Int. Ed. 2018, 57, 10080–10084). The calculated fluoride ion affinities (FIA) of 1–9 are higher than that of SbF5, which classifies them as Lewis superacids.
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- 2022
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3. Unmasking the constitution and bonding of the proposed lithium nickelate “Li3NiPh3(solv)3”: revealing the hidden C6H4 ligand
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Somerville, Rosie J., primary, Borys, Andryj M., additional, Perez-Jimenez, Marina, additional, Nova, Ainara, additional, Balcells, David, additional, Malaspina, Lorraine A., additional, Grabowsky, Simon, additional, Carmona, Ernesto, additional, Hevia, Eva, additional, and Campos, Jesús, additional
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- 2022
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4. BN-Substitution in Dithienylpyrenes Prevents Excimer Formation in Solution and in the Solid State
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Appiarius, Yannik, Gliese, Philipp J, Segler, Stephan A W, Rusch, Pascal, Zhang, Jiangbin, Gates, Paul J, Pal, Rumpa, Malaspina, Lorraine A, Sugimoto, Kunihisa, Neudecker, Tim, Bigall, Nadja C, Grabowsky, Simon, Bakulin, Artem A, Staubitz, Anne, Appiarius, Yannik [0000-0002-9849-6950], Gates, Paul J [0000-0001-8619-7745], Neudecker, Tim [0000-0001-7599-3578], Bigall, Nadja C [0000-0003-0171-1106], Grabowsky, Simon [0000-0002-3377-9474], Bakulin, Artem A [0000-0002-3998-2000], Staubitz, Anne [0000-0002-9040-3297], and Apollo - University of Cambridge Repository
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3402 Inorganic Chemistry ,General Energy ,34 Chemical Sciences ,540 Chemistry ,570 Life sciences ,biology ,Physical and Theoretical Chemistry ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials - Abstract
Boron-nitrogen substitutions in polycyclic aromatic hydrocarbons (PAHs) have a strong impact on the optical properties of the molecules due to a significantly more heterogeneous electron distribution. However, besides these single-molecule properties, the observed optical properties of PAHs critically depend on the degree of intermolecular interactions such as ��-��-stacking, dipolar interactions, or the formation of dimers in the excited state. Pyrene is the most prominent example showing the latter as it exhibits a broadened and strongly bathochromically shifted emission band at high concentrations in solution compared to the respective monomers. In the solid state, the impact of intermolecular interactions is even higher as it determines the crystal packing crucially. In this work, a thiophene-flanked BN-pyrene (BNP) was synthesized and compared with its all-carbon analogue (CCP) in solution and in the solid state by means of crystallography, NMR spectroscopy, UV-vis spectroscopy, and photoluminescence (PL) spectroscopy. In solution, PL spectroscopy revealed the solvent-dependent presence of excimers of CCP at high concentrations. In contrast, no excimers were found in BNP. Clear differences were also observed in the single-crystal packing motifs. While CCP revealed overlapped pyrene planes with centroid distances in the range of classical ��-stacking interactions, the BNP scaffolds were displaced and significantly more spatially separated.
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- 2021
5. Perfluorinated Trialkoxysilanol with Dramatically Increased Br��nsted Acidity
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Feige, Felix, Malaspina, Lorraine A., Rychagova, Elena, Ketkov, Sergey, Grabowsky, Simon, Hupf, Emanuel, and Beckmann, Jens
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540 Chemistry ,570 Life sciences ,biology - Abstract
The Br��nsted acidity of the perfluorinated trialkoxysilanol {(F3C)3CO}3SiOH is more than 13 orders of magnitude higher than that of orthosilicic acid, Si(OH)4, and even more for most previously known silanols. It is easily deprotonated by simple amines and pyridines to give the conjugate silanolates [OSi{OC(CF3)3}3]
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- 2021
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6. Relativistic Hirshfeld atom refinement of an organo-gold(I) compound
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Pawlędzio, Sylwia, primary, Malinska, Maura, additional, Woińska, Magdalena, additional, Wojciechowski, Jakub, additional, Andrade Malaspina, Lorraine, additional, Kleemiss, Florian, additional, Grabowsky, Simon, additional, and Woźniak, Krzysztof, additional
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- 2021
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7. Unmasking the constitution and bonding of the proposed lithium nickelate "Li3NiPh3(solv)3": revealing the hidden C6H4 ligand.
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Somerville, Rosie J., Borys, Andryj M., Perez-Jimenez, Marina, Nova, Ainara, Balcells, David, Malaspina, Lorraine A., Grabowsky, Simon, Carmona, Ernesto, Hevia, Eva, and Campos, Jesús
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- 2022
- Full Text
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8. Accurate crystal structures and chemical properties from NoSpherA2
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Kleemiss, Florian, primary, Dolomanov, Oleg V., additional, Bodensteiner, Michael, additional, Peyerimhoff, Norbert, additional, Midgley, Laura, additional, Bourhis, Luc J., additional, Genoni, Alessandro, additional, Malaspina, Lorraine A., additional, Jayatilaka, Dylan, additional, Spencer, John L., additional, White, Fraser, additional, Grundkötter-Stock, Bernhard, additional, Steinhauer, Simon, additional, Lentz, Dieter, additional, Puschmann, Horst, additional, and Grabowsky, Simon, additional
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- 2021
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9. The advanced treatment of hydrogen atoms in quantum crystallography
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Andrade Malaspina, Lorraine, Overgaard, Jacob, Grabowsky, Simon, and Englert, Ullrich
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determination ,Crystal structure ,ddc:540 ,540 Chemistry - Abstract
Crystal structure determination using X-ray diffraction has become a routine technique for life and materials sciences, chemistry, biology, physics, etc. since its discovery 106 years ago. Despite its long existence, the most widely used model for crystal structure refinement is still the hundred-years old Independent Atom Model (IAM), which neglects chemical information present in the experimental data, such as bonding densities and densities due to lone electron pair regions. Over the past decades, new models have been developed to include this chemical information via aspherical description of atoms either using multipole-based techniques, maximum entropy methods or wavefunction-based techniques. The latter constitute the recently emerged field of quantum crystallography, combining quantum theory and crystallography to provide advanced structure refinements and wavefunctions with embedded information from experiment, giving access to experimental electron density distributions. In this thesis, we show the different models that allow access to these chemical information present in the experimental data, explaining the theory behind the atomic scattering factors, and their different sources according to each different model. These are employed and tested thoroughly for cases where the spherical approach (independent atom model) using X-ray diffraction data fails most dramatically: hydrogen atoms. We show how to obtain accurate atomic parameters for hydrogen atoms in unusual bonding situations using X-ray diffraction data only. These include hydrogen atoms in tautomeric equilibrium (Chapter 8), involved in bridging positions within strong intramolecular hydrogen bonds (Chapters 9, 9.2 and Section 10.2), involved in agostic interactions, bonded to heavy elements (Chapter 11) and in proteins (Chapter 12). Correlations between hydrogen atoms displacement parameters and their positions are evaluated through their congruent refinement using state of the art methods for the estimation of anisotropic displacement parameters (Chapter 10.2). We compare derived X-H bond lengths and ADPs to those obtained from neutron diffraction data as reference. We demonstrate that the effects of the electric field imposed by the crystal environment for ionic systems plays an important role on the location of the mobile hydrogen atom inside strong intramolecular hydrogen bonds for the hydrogen maleate class of compounds (Chapter 9.2). The results obtained here lead to the development of a software (lamaGOET) and a new method, namely the HAR-ELMO method (Chapter 12). Successful applications of Hirshfeld Atom Refinement and HAR-ELMO for systems including transition metal hydrides and proteins are presented for the first time using the developed software and method (Chapter 11 and 12), where quantum crystallography’s powerful tools are tested to obtain properties for molecules which are dependent on accurate determination of their hydrogen atom parameters such as agostic interactions.
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- 2020
10. Hydrogen atoms in bridging positions from quantum crystallographic refinements: influence of hydrogen atom displacement parameters on geometry and electron density
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Malaspina, Lorraine A., Hoser, Anna A., Edwards, Alison J., Woińska, Magdalena, Turner, Michael J., Price, Jason R., Sugimoto, Kunihisa, Nishibori, Eiji, Bürgi, Hans-Beat, Jayatilaka, Dylan, Grabowsky, Simon, University of Zurich, and Grabowsky, Simon
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10120 Department of Chemistry ,3104 Condensed Matter Physics ,540 Chemistry ,570 Life sciences ,biology ,1600 General Chemistry ,General Materials Science ,Physics::Atomic Physics ,General Chemistry ,Condensed Matter Physics ,2500 General Materials Science - Abstract
Resonance-assisted hydrogen bonds (RAHBs) are exploited in chemical synthesis or serve as models for biologically relevant proton-transfer reactions [K. T. Mahmudov and A. J. L. Pombeiro, Chem. – Eur. J., 2016, 22, 16356–16398]. Their properties depend on the position of the hydrogen atom between donor and acceptor atoms. In the intramolecular RAHB of hydrogen maleate salts, this position is strongly influenced by the counter cation and varies from highly asymmetric to perfectly symmetric. This compound class is therefore ideally suited to investigate the factors determining geometry and electron density of intramolecular RAHBs. Here, it is shown that Hirshfeld atom refinements (HARs) of X-ray diffraction data of different hydrogen maleate salts can accurately and precisely match the hydrogen atom positions obtained from neutron diffraction and are independent of the model used for the hydrogen atom displacement parameters. Thus, the simplest, i.e. isotropic, HAR model can be used to locate hydrogen atoms also in bridging positions. In contrast, the determination of electron-density parameters with X-ray constrained wavefunction (XCW) fitting requires anisotropic, highly accurate hydrogen atom displacement parameters.
- Published
- 2020
11. Biochemical ans structural studies of cellobiohydrolase and endoxylanase enzymes of the fungus Humicola grisea var. thermoidea
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Malaspina, Lorraine Andrade, Marques, Ivo de Almeida, Faria, Fabrícia Paula de, Ulhoa, Cirano José, and Valadares, Napoleão Fonseca
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X-ray ,Crystallography ,Macromoléculas ,Macromolecules ,Cristalografia ,FISICA [CIENCIAS EXATAS E DA TERRA] ,Humicola grisea ,Raio X - Abstract
A obten c~ao da estrutura tridimensional de uma enzima pode ser utilizada como passo inicial em projetos de engenharia gen etica e engenharia enzim atica com intuito de optimiza c~ao da atividade catal tica e/ou a produ c~ao em escala industrial de enzimas alvo. Atualmente, a cristalogra a e o m etodo mais empregado para a determina c~ao de estruturas tridimensionais de macromol eculas. A biomassa vegetal, na forma de celulose, hemicelulose e lignina, apresenta grande potencial para aplica c~oes biotecnol ogicas. Com a crescente demanda por fontes renov aveis de energia, tem-se proposto sua utiliza c~ao para a obten c~ao de energia, os ditos biocombust veis. Para esse m, a principal abordagem que se tem procurado e a degrada c~ao da biomassa via hidr olise enzim atica. Neste contexto, o estudo de micro-organismos capazes de realizar a degrada c~ao da biomassa e o estudo das enzimas envolvidas no processo apresentam papel chave. Particularmente, o fungo term o lo Humicola grisea var. thermoidea apresenta produ c~ao signi cativa de enzimas lignocelulol ticas ativas a alta temperatura e tem sido considerado um forte candidato para aplica c~oes industriais. Contudo, a literatura cient ca ainda carece de informa c~oes estruturais sobre as enzimas do fungo envolvidas na hidr olise da lignocelulose. Em trabalhos anteriores, a enzima celulol tica celobiohidrolase (CBH1.2) de H. grisea foi identi cada e clonada em Pichia pastoris bem como uma das endoxilanases (HXYN2) deste mesmo organismo. Neste projeto de mestrado, foram expressadas as enzimas CBH1.2 e HXYN2 utilizando sistema heter ologo de express~ao, obtendo rendimento satisfat orio para ensaios in vitro. Foram estabelecidos protocolos de puri ca c~ao via precipita c~ao por sulfato de am^onio e realizados experimentos iniciais de atividade enzim atica via o m etodo dos a c ucares redutores para as duas enzimas. XVIII Foi encontrada condi c~ao de cristaliza c~ao para a enzima CBH1.2r onde foram obtidos pequenos cristais em forma de agulha nos ensaios de cristaliza c~ao. Al em deste, tamb em foi realizada a clonagem da enzima CBH1.2 de Humicola grisea no vetor de express~ao pHIL-D2 (para express~ao extracelular). Este vetor foi utilizado para transformar as linhagens SMD1168 e GS115 da levedura P. pastoris ambas com o gen otipo his4-. Foram detectados transformantes capazes de secretar a prote na ativa em ambas as linhagens. Obtaining 3-dimensional structure of an enzyme can be used as an initial step in projects of genetic engineering and enzymatic engineering when aiming for optimization of catalytic activity and/or production of target enzymes on an industrial scale. Currently, crystallography is the most widely used method for the determination of three-dimensional structures of macromolecules. The plant biomass in the form of cellulose, hemicellulose and lignin, have great potential for biotechnological applications. With the growing demand for renewable energy sources, its been proposed it's use to obtain energy, called biofuels. For such purpose, the main approach is the search of the degradation of biomass via enzymatic hydrolysis. In this context, the study of microorganisms capable of carrying out the degradation of biomass and the study of the enzymes involved in this process play a key role. Particularly, the thermophilic fungus Humicola grisea var. thermoidea presents signi cant production of active lignocellulolytic enzymes at high temperature and has been considered a strong candidate for industrial applications. However, the scienti c literature still lacks of structural information on fungal enzymes involved in the hydrolysis of lignocellulose. In previous work, the cellulolytic enzyme cellobiohydrolase (CBH1.2) from Humicola grisea has been identi ed and cloned into Pichia pastoris as well as one of the endoxylanases (HXYN2) from this same organism. In this master's project, the enzymes CBH1.2 and HXYN2 were expressed using heterologous expression system obtaining satisfactory yield for in vitro assays. Puri - cation protocols were established via precipitation by ammonium sulfate and initial experiments of enzyme activity were performed via the reducing sugars method for both enzymes. XX Crystallization conditions were found for the enzyme CBH1.2r, where small needleshaped crystals were obtained in crystallization trials. In addition to this, the cloning of the enzyme CBH1.2 from Humicola grisea with the pHIL-D2 expression vector (for extracellular expression) was performed. This vector was used to transform GS115 and SMD1168 strains of the yeast P. pastoris both with the genotype his4-. Transformants that were able to secrete active protein were detected in both strains. Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES
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- 2014
12. Towards Hexagonal Planar Nickel: A Dispersionstabilised Tri-Lithium Nickelate.
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Borys, Andryj M., Malaspina, Lorraine A., Grabowsky, Simon, and Hevia, Eva
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- 2022
- Full Text
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13. The advanced treatment of hydrogen bonding in quantum crystallography
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Malaspina, Lorraine, Genoni, Alessandro, Jayatilaka, Dylan, Turner, Michael J., Sugimoto, Kunihisa, Nishibori, Eiji, and Grabowsky, Simon
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540 Chemistry ,570 Life sciences ,biology ,3. Good health
14. Lattice response to the radiation damage of molecular crystals: radiation-induced versus thermal expansivity.
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McMonagle CJ, Fuller CA, Hupf E, Malaspina LA, Grabowsky S, and Chernyshov D
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The interaction of intense synchrotron radiation with molecular crystals frequently modifies the crystal structure by breaking bonds, producing fragments and, hence, inducing disorder. Here, a second-rank tensor of radiation-induced lattice strain is proposed to characterize the structural susceptibility to radiation. Quantitative estimates are derived using a linear response approximation from experimental data collected on three materials Hg(NO
3 )2 (PPh3 )2 , Hg(CN)2 (PPh3 )2 and BiPh3 [PPh3 = triphenylphosphine, P(C6 H5 )3 ; Ph = phenyl, C6 H5 ], and are compared with the corresponding thermal expansivities. The associated eigenvalues and eigenvectors show that the two tensors are not the same and therefore probe truly different structural responses. The tensor of radiative expansion serves as a measure of the susceptibility of crystal structures to radiation damage., (open access.)- Published
- 2024
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15. Unmasking the constitution and bonding of the proposed lithium nickelate "Li 3 NiPh 3 (solv) 3 ": revealing the hidden C 6 H 4 ligand.
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Somerville RJ, Borys AM, Perez-Jimenez M, Nova A, Balcells D, Malaspina LA, Grabowsky S, Carmona E, Hevia E, and Campos J
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More than four decades ago, a complex identified as the planar homoleptic lithium nickelate "Li
3 NiPh3 (solv)3 " was reported by Taube and co-workers. This and subsequent reports involving this complex have lain dormant since; however, the absence of an X-ray diffraction structure leaves questions as to the nature of the Ni-PhLi bonding and the coordination geometry at Ni. By systematically evaluating the reactivity of Ni(COD)2 with PhLi under different conditions, we have found that this classical molecule is instead a unique octanuclear complex, [{Li3 (solv)2 Ph3 Ni}2 (μ-η2 :η2 -C6 H4 )] (5). This is supported by X-ray crystallography and solution-state NMR studies. A theoretical bonding analysis from NBO, QTAIM, and ELI perspectives reveals extreme back-bonding to the bridging C6 H4 ligand resulting in dimetallabicyclobutane character, the lack of a Ni-Ni bond, and pronounced σ-bonding between the phenyl carbanions and nickel, including a weak σC-Li → sNi interaction with the C-Li bond acting as a σ-donor. Employing PhNa led to the isolation of [Na2 (solv)3 Ph2 NiCOD]2 (7) and [Na2 (solv)3 Ph2 (NaC8 H11 )Ni(COD)]2 (8), which lack the benzyne-derived ligand. These findings provide new insights into the synthesis, structure, bonding and reactivity of heterobimetallic nickelates, whose prevalence in organonickel chemistry and catalysis is likely greater than previously believed., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)- Published
- 2022
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16. Accurate crystal structures and chemical properties from NoSpherA2.
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Kleemiss F, Dolomanov OV, Bodensteiner M, Peyerimhoff N, Midgley L, Bourhis LJ, Genoni A, Malaspina LA, Jayatilaka D, Spencer JL, White F, Grundkötter-Stock B, Steinhauer S, Lentz D, Puschmann H, and Grabowsky S
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The relationship between the structure and the properties of a drug or material is a key concept of chemistry. Knowledge of the three-dimensional structure is considered to be of such importance that almost every report of a new chemical compound is accompanied by an X-ray crystal structure - at least since the 1970s when diffraction equipment became widely available. Crystallographic software of that time was restricted to very limited computing power, and therefore drastic simplifications had to be made. It is these simplifications that make the determination of the correct structure, especially when it comes to hydrogen atoms, virtually impossible. We have devised a robust and fast system where modern chemical structure models replace the old assumptions, leading to correct structures from the model refinement against standard in-house diffraction data using no more than widely available software and desktop computing power. We call this system NoSpherA2 (Non-Spherical Atoms in Olex2). We explain the theoretical background of this technique and demonstrate the far-reaching effects that the improved structure quality that is now routinely available can have on the interpretation of chemical problems exemplified by five selected examples., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)
- Published
- 2020
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