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Destro R, Barzaghi M, Soave R, Roversi P, Lo Presti L. Accurate experimental characterization of the labile N–Cl bond in N-chloro- N′-( p-fluorophenyl)-benzamidine crystal at 17.5 K. CrystEngComm 2022. [DOI: 10.1039/d2ce00957a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Very low temperature can preserve the photolabile N–Cl bond in a N-chloro-N-benzamidine derivative long enough to carry on an accurate experimental X-ray charge density study.
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Affiliation(s)
- Riccardo Destro
- Università degli Studi di Milano, Department of Chemistry, Via Golgi 19, 20133 Milano, Italy
| | - Mario Barzaghi
- Consiglio Nazionale delle Ricerche (CNR), Piazzale Aldo Moro 7, 00185 Roma, Italy
| | - Raffaella Soave
- Consiglio Nazionale delle Ricerche (CNR), Istituto di Scienze E Tecnologie Chimiche “Giulio Natta” (SCITEC), Via Golgi 19, 20133 Milano, Italy
| | - Pietro Roversi
- Consiglio Nazionale delle Ricerche (CNR), Istituto di Biologia e Biotecnologia Agraria (IBBA), Via Bassini 15, 20133 Milano, Italy
- Leicester Institute of Chemical and Structural Biology and Department of Molecular and Cell Biology, University of Leicester, Henry Wellcome Building, Lancaster Road, Leicester LE1 7HR, UK
| | - Leonardo Lo Presti
- Università degli Studi di Milano, Department of Chemistry, Via Golgi 19, 20133 Milano, Italy
- Istituto Nazionale di Fisica Nucleare (INFN), Laboratori Nazionali di Frascati, Frascati, Italy
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2
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Baillargeon P, Seidler T, Champagne B, Soldera A. Polar and Helical Isomorphous Crystals of Proline Derivatives: Influence of a Fluorine Atom on the Electric Susceptibility. CHEMISTRY AFRICA 2021. [DOI: 10.1007/s42250-021-00236-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
AbstractTwo novel nonlinear optical isomorphous crystals of proline derivatives with alkyne functionality have been obtained (Boc-L-ProNH(CH2)2CCH and Boc-cis-4-fluoro-L-ProNH(CH2)2CCH). Both derivatives, which differ only by the substitution of a H atom to a F atom, adopt the same polar and columnar right-handed helix arrangement in the crystalline state. In addition, adjacent polar helical columns all point in the same direction, thus generating a macrodipole and a crystalline system conducive for second harmonic generation (SHG) properties. This isomorphous crystal system constitutes an interesting tool to study the effect of the fluorine atom on the dipole moment and on the first hyperpolarizability. Starting from the PBC optimized geometries of the crystals, the macroscopic second-order nonlinearity, χ(2), of the newly synthesized crystals has been estimated by quantum chemical calculations. These χ(2) responses are of the same order of magnitude as those of inorganic proline derivatives while smaller than those observed in crystals of push–pull π-conjugated molecules.
Graphic Abstract
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Fernández-Alarcón A, Guevara-Vela JM, Casals-Sainz JL, Costales A, Francisco E, Martín Pendás Á, Rocha Rinza T. Photochemistry in Real Space: Batho- and Hypsochromism in the Water Dimer. Chemistry 2020; 26:17035-17045. [PMID: 32822523 DOI: 10.1002/chem.202002854] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2020] [Indexed: 11/09/2022]
Abstract
The development of chemical intuition in photochemistry faces several difficulties that result from the inadequacy of the one-particle picture, the Born-Oppenheimer approximation, and other basic ideas used to build models. It is shown herein how real-space approaches can be efficiently used to gain valuable insights in photochemistry through a simple example of red and blue shift effects: the double hypso- and bathochromic shifts in the low-lying valence excited states of (H2 O)2 . It is demonstrated that 1) the use of these techniques allows the perturbative language used in the theory of intermolecular interactions, even in the strongly interacting short-range regime, to be maintained; 2) one and only one molecule is photoexcited in each of the addressed excited states and 3) the electrostatic interaction between the in-the-cluster molecular dipoles provides a fairly intuitive rationalisation of the observed batho- and hypsochromism. The methods exploited and illustrated herein are able to maintain the individuality and properties of the interacting entities in a molecular aggregate, and thereby they allow chemical intuition in general states, at any geometry and using a broad variety of electronic structure methods to be kept and built.
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Affiliation(s)
- Alberto Fernández-Alarcón
- Institute of Chemistry, National Autonomous University of Mexico, 04510, Mexico City, Mexico.,Department of Analytical and Physical Chemistry, University of Oviedo, 33006, Oviedo, Spain
| | | | - José Luis Casals-Sainz
- Department of Analytical and Physical Chemistry, University of Oviedo, 33006, Oviedo, Spain
| | - Aurora Costales
- Department of Analytical and Physical Chemistry, University of Oviedo, 33006, Oviedo, Spain
| | - Evelio Francisco
- Department of Analytical and Physical Chemistry, University of Oviedo, 33006, Oviedo, Spain
| | - Ángel Martín Pendás
- Department of Analytical and Physical Chemistry, University of Oviedo, 33006, Oviedo, Spain
| | - Tomás Rocha Rinza
- Institute of Chemistry, National Autonomous University of Mexico, 04510, Mexico City, Mexico
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4
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Korlyukov AA, Nelyubina YV. Quantum chemical methods in charge density studies from X-ray diffraction data. RUSSIAN CHEMICAL REVIEWS 2019. [DOI: 10.1070/rcr4866] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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5
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Köhler C, Lübben J, Krause L, Hoffmann C, Herbst-Irmer R, Stalke D. Comparison of different strategies for modelling hydrogen atoms in charge density analyses. ACTA CRYSTALLOGRAPHICA SECTION B, STRUCTURAL SCIENCE, CRYSTAL ENGINEERING AND MATERIALS 2019; 75:434-441. [PMID: 32830665 DOI: 10.1107/s2052520619004517] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2019] [Accepted: 04/03/2019] [Indexed: 06/11/2023]
Abstract
The quality of various approximation methods for modelling anisotropic displacement parameters (ADPs) for hydrogen atoms was investigated in a comparative study. A multipole refinement was performed against high-resolution single crystal X-ray data of 9-diphenylthiophosphoranylanthracene (SPAnH) and 9,10-bis-diphenylthiophosphoranylanthracene·toluene (SPAnPS). Hydrogen-atom parameters and structural properties derived from our collected neutron data sets were compared with those obtained from the SHADE-server, the software APD-Toolkit based on the invariom database, the results from Hirshfeld atom refinement conducted in the OLEX2 GUI (HARt), and the results of anisotropic hydrogen refinement within XD2016. Additionally, a free refinement of H-atom positions against X-ray data was performed with fixed ADPs from various methods. The resulting C-H bond distances were compared with distances from neutron diffraction experiments and the HARt results. Surprisingly, the refinement of anisotropic hydrogen displacement parameters against the X-ray data yielded the smallest deviations from the neutron values. However, the refinement of bond-directed quadrupole parameters turned out to be vital for the quality of the resulting ADPs. In both model structures, SHADE and, to a lesser extent, APD-Toolkit showed problems in dealing with atoms bonded to carbon atoms with refined Gram-Charlier parameters for anharmonic motion. The HARt method yields the most accurate C-H bond distances compared to neutron data results. Unconstrained refinement of hydrogen atom positions using ADPs derived from all other used approximation methods showed that even with well approximated hydrogen ADPs, the resulting distances were still significantly underestimated.
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Affiliation(s)
- Christian Köhler
- Institut für Anorganische Chemie, Universität Göttingen, Tammannstrasse 4, 37077 Göttingen, Germany
| | - Jens Lübben
- Institut für Anorganische Chemie, Universität Göttingen, Tammannstrasse 4, 37077 Göttingen, Germany
| | - Lennard Krause
- Department of Chemistry, Aarhus University, Langelandsgade 140, Aarhus, 8000, Denmark
| | - Christina Hoffmann
- Neutron Sciences Directorate, Oak Ridge National Laboratory, 1 Bethel Valley Rd, Oak Ridge, TN 37831, USA
| | - Regine Herbst-Irmer
- Institut für Anorganische Chemie, Universität Göttingen, Tammannstrasse 4, 37077 Göttingen, Germany
| | - Dietmar Stalke
- Institut für Anorganische Chemie, Universität Göttingen, Tammannstrasse 4, 37077 Göttingen, Germany
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6
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Topology of electron density and electrostatic potential of HIV reverse transcriptase inhibitor zidovudine from high resolution X-ray diffraction and charge density analysis. J Mol Struct 2019. [DOI: 10.1016/j.molstruc.2018.11.098] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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7
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Shi MW, Thomas SP, Hathwar VR, Edwards AJ, Piltz RO, Jayatilaka D, Koutsantonis GA, Overgaard J, Nishibori E, Iversen BB, Spackman MA. Measurement of Electric Fields Experienced by Urea Guest Molecules in the 18-Crown-6/Urea (1:5) Host-Guest Complex: An Experimental Reference Point for Electric-Field-Assisted Catalysis. J Am Chem Soc 2019; 141:3965-3976. [PMID: 30761898 DOI: 10.1021/jacs.8b12927] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
High-resolution synchrotron and neutron single-crystal diffraction data of 18-crown-6/(pentakis)urea measured at 30 K are combined, with the aim of better appreciating the electrostatics associated with intermolecular interactions in condensed matter. With two 18-crown-6 molecules and five different urea molecules in the crystal, this represents the most ambitious combined X-ray/synchrotron and neutron experimental charge density analysis to date on a cocrystal or host-guest system incorporating such a large number of unique molecules. The dipole moments of the five urea guest molecules in the crystal are enhanced considerably compared to values determined for isolated molecules, and 2D maps of the electrostatic potential and electric field show clearly how the urea molecules are oriented with dipole moments aligned along the electric field exerted by their molecular neighbors. Experimental electric fields in the range of 10-19 GV m-1, obtained for the five different urea environments, corroborate independent measurements of electric fields in the active sites of enzymes and provide an important experimental reference point for recent discussions focused on electric-field-assisted catalysis.
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Affiliation(s)
- Ming W Shi
- School of Molecular Sciences , University of Western Australia , 35 Stirling Highway , Crawley , WA 6009 , Australia
| | - Sajesh P Thomas
- School of Molecular Sciences , University of Western Australia , 35 Stirling Highway , Crawley , WA 6009 , Australia.,Center for Materials Crystallography and Department of Chemistry , Aarhus University , Langelandsgade 140 , DK-8000 Aarhus C , Denmark
| | - Venkatesha R Hathwar
- Center for Materials Crystallography and Department of Chemistry , Aarhus University , Langelandsgade 140 , DK-8000 Aarhus C , Denmark.,Division of Physics, Faculty of Pure and Applied Sciences , University of Tsukuba , 1-1-1 Tennodai , Tsukuba , Ibaraki 305-8571 , Japan
| | - Alison J Edwards
- Australian Nuclear Science and Technology Organization , Australian Centre for Neutron Scattering , New Illawarra Road , Lucas Heights , New South Wales 2234 , Australia
| | - Ross O Piltz
- Australian Nuclear Science and Technology Organization , Australian Centre for Neutron Scattering , New Illawarra Road , Lucas Heights , New South Wales 2234 , Australia
| | - Dylan Jayatilaka
- School of Molecular Sciences , University of Western Australia , 35 Stirling Highway , Crawley , WA 6009 , Australia
| | - George A Koutsantonis
- School of Molecular Sciences , University of Western Australia , 35 Stirling Highway , Crawley , WA 6009 , Australia
| | - Jacob Overgaard
- Center for Materials Crystallography and Department of Chemistry , Aarhus University , Langelandsgade 140 , DK-8000 Aarhus C , Denmark
| | - Eiji Nishibori
- Division of Physics, Faculty of Pure and Applied Sciences , University of Tsukuba , 1-1-1 Tennodai , Tsukuba , Ibaraki 305-8571 , Japan
| | - Bo B Iversen
- Center for Materials Crystallography and Department of Chemistry , Aarhus University , Langelandsgade 140 , DK-8000 Aarhus C , Denmark
| | - Mark A Spackman
- School of Molecular Sciences , University of Western Australia , 35 Stirling Highway , Crawley , WA 6009 , Australia
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8
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Woińska M, Jayatilaka D, Dittrich B, Flaig R, Luger P, Woźniak K, Dominiak PM, Grabowsky S. Validation of X-ray Wavefunction Refinement. Chemphyschem 2017; 18:3334-3351. [PMID: 29168318 DOI: 10.1002/cphc.201700810] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2017] [Revised: 09/22/2017] [Indexed: 11/10/2022]
Abstract
In this work, the quality of the electron density in crystals reconstructed by the multipolar model (MM) and by X-ray wavefunction refinement (XWR) is tested on a set of high-resolution X-ray diffraction data sets of four amino acids and six tripeptides. It results in the first thorough validation of XWR. Agreement statistics, figures of merit, residual- and deformation-density maps, as well as atomic displacement parameters are used to measure the quality of the reconstruction relative to the measured structure factors. Topological analysis of the reconstructed density is carried out to obtain atomic and bond-topological properties, which are subsequently compared to the values derived from benchmarking periodic DFT geometry optimizations. XWR is simultaneously in better agreement than the MM with both benchmarking theory and the measured diffraction pattern. In particular, the obvious problems with the description of polar bonds in the MM are significantly reduced by using XWR. Similarly, modeling of electron density in the vicinity of hydrogen atoms with XWR is visibly improved.
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Affiliation(s)
- Magdalena Woińska
- Biological and Chemical Research Centre, Chemistry Department, University of Warsaw, Zwirki i Wigury 101, 02-089, Warsaw, Poland
| | - Dylan Jayatilaka
- School of Molecular Sciences, The University of Western Australia, 35 Stirling Highway, Perth, WA, 6009, Australia
| | - Birger Dittrich
- Heinrich-Heine-Universität Düsseldorf, Anorganische Chemie und Strukturchemie, Gebäude 26.42.01.21, Universitätsstraße 1, 40225, Düsseldorf, Germany
| | - Ralf Flaig
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxon, OX11 0DE, UK
| | - Peter Luger
- Freie Universität Berlin, Institut für Chemie und Biochemie, Fabeckstraße 36a, 14195, Berlin, Germany
| | - Krzysztof Woźniak
- Biological and Chemical Research Centre, Chemistry Department, University of Warsaw, Zwirki i Wigury 101, 02-089, Warsaw, Poland
| | - Paulina M Dominiak
- Biological and Chemical Research Centre, Chemistry Department, University of Warsaw, Zwirki i Wigury 101, 02-089, Warsaw, Poland
| | - Simon Grabowsky
- Institut für Anorganische Chemie und Kristallographie, Fachbereich 2-Biologie/Chemie, Universität Bremen, Leobener Straße NW2, 28359, Bremen, Germany
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9
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Nassour A, Domagala S, Guillot B, Leduc T, Lecomte C, Jelsch C. A theoretical-electron-density databank using a model of real and virtual spherical atoms. ACTA CRYSTALLOGRAPHICA SECTION B, STRUCTURAL SCIENCE, CRYSTAL ENGINEERING AND MATERIALS 2017; 73:610-625. [PMID: 28762971 DOI: 10.1107/s2052520617008204] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Accepted: 06/02/2017] [Indexed: 06/07/2023]
Abstract
A database describing the electron density of common chemical groups using combinations of real and virtual spherical atoms is proposed, as an alternative to the multipolar atom modelling of the molecular charge density. Theoretical structure factors were computed from periodic density functional theory calculations on 38 crystal structures of small molecules and the charge density was subsequently refined using a density model based on real spherical atoms and additional dummy charges on the covalent bonds and on electron lone-pair sites. The electron-density parameters of real and dummy atoms present in a similar chemical environment were averaged on all the molecules studied to build a database of transferable spherical atoms. Compared with the now-popular databases of transferable multipolar parameters, the spherical charge modelling needs fewer parameters to describe the molecular electron density and can be more easily incorporated in molecular modelling software for the computation of electrostatic properties. The construction method of the database is described. In order to analyse to what extent this modelling method can be used to derive meaningful molecular properties, it has been applied to the urea molecule and to biotin/streptavidin, a protein/ligand complex.
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Affiliation(s)
- Ayoub Nassour
- Laboratoire de Cristallographie, Résonance Magnétique et Modélisations (CRM2), CNRS, UMR 7036, Institut Jean Barriol, Faculté des Sciences et Technologies, Université de Lorraine, BP 70239, 54506 Vandoeuvre-lès-Nancy Cedex, France
| | - Slawomir Domagala
- Department of Chemistry, University of Warsaw, ul. Pasteura 1, 02-093 Warsaw, Poland
| | - Benoit Guillot
- Laboratoire de Cristallographie, Résonance Magnétique et Modélisations (CRM2), CNRS, UMR 7036, Institut Jean Barriol, Faculté des Sciences et Technologies, Université de Lorraine, BP 70239, 54506 Vandoeuvre-lès-Nancy Cedex, France
| | - Theo Leduc
- Laboratoire de Cristallographie, Résonance Magnétique et Modélisations (CRM2), CNRS, UMR 7036, Institut Jean Barriol, Faculté des Sciences et Technologies, Université de Lorraine, BP 70239, 54506 Vandoeuvre-lès-Nancy Cedex, France
| | - Claude Lecomte
- Laboratoire de Cristallographie, Résonance Magnétique et Modélisations (CRM2), CNRS, UMR 7036, Institut Jean Barriol, Faculté des Sciences et Technologies, Université de Lorraine, BP 70239, 54506 Vandoeuvre-lès-Nancy Cedex, France
| | - Christian Jelsch
- Laboratoire de Cristallographie, Résonance Magnétique et Modélisations (CRM2), CNRS, UMR 7036, Institut Jean Barriol, Faculté des Sciences et Technologies, Université de Lorraine, BP 70239, 54506 Vandoeuvre-lès-Nancy Cedex, France
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10
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Hulliger J, Burgener M, Hesterberg R, Sommer M, Brahimi K, Aboulfadl H. Stochastic polarity formation in molecular crystals, composite materials and natural tissues. IUCRJ 2017; 4:360-368. [PMID: 28875023 PMCID: PMC5571799 DOI: 10.1107/s205225251700700x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Accepted: 05/10/2017] [Indexed: 05/11/2023]
Abstract
This topical review summarizes the theoretical and experimental findings obtained over the last 20 years on the subject of growth-induced polarity formation driven by a Markov chain process. When entering the growing surface of a molecular crystal, an inorganic-organic composite or a natural tissue, the building blocks may undergo 180° orientational disorder. Driven by configurational entropy, faulted orientations can promote the conversion of a growing non-polar seed into an object showing polar domains. Similarly, orientational disorder at the interface may change a polar seed into a two-domain state. Analytical theory and Monte Carlo simulations were used to model polarity formation. Scanning pyroelectric, piezoresponse force and phase-sensitive second-harmonic microscopies are methods for investigating the spatial distribution of polarity. Summarizing results from different types of materials, a general principle is provided for obtaining growth-induced polar domains: a non-zero difference in the probabilities for 180° orientational misalignments of building blocks, together with uni-directional growth, along with Markov chain theory, can produce objects showing polar domains.
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Affiliation(s)
- Jürg Hulliger
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, Bern CH-3012, Switzerland
- Correspondence e-mail:
| | - Matthias Burgener
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, Bern CH-3012, Switzerland
| | - Rolf Hesterberg
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, Bern CH-3012, Switzerland
| | - Martin Sommer
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, Bern CH-3012, Switzerland
| | - Khadidja Brahimi
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, Bern CH-3012, Switzerland
| | - Hanane Aboulfadl
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, Bern CH-3012, Switzerland
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11
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Dittrich B. Is there a future for topological analysis in experimental charge-density research? ACTA CRYSTALLOGRAPHICA SECTION B-STRUCTURAL SCIENCE CRYSTAL ENGINEERING AND MATERIALS 2017; 73:325-329. [DOI: 10.1107/s2052520617006680] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Accepted: 05/03/2017] [Indexed: 11/11/2022]
Abstract
Topological analysis using Bader and co-worker'sAtoms in Moleculestheory has seen many applications in theoretical chemistry and experimental charge-density research. A brief overview of successful early developments, establishing topological analysis as a research tool for characterizing intramolecular chemical bonding, is provided. A lack of vision in many `descriptive but not predictive' subsequent studies is discussed. Limitations of topology for providing accurate energetic estimates of intermolecular interaction energies are put into perspective. It is recommended that topological analyses of well understood bonding situations are phased out and are only reported for unusual bonding. Descriptive studies of intermolecular interactions should have a clear research focus.
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Solid state characterization and theoretical study of non-linear optical properties of a Fluoro-N-Acylhydrazide derivative. PLoS One 2017; 12:e0175859. [PMID: 28437446 PMCID: PMC5402957 DOI: 10.1371/journal.pone.0175859] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2016] [Accepted: 03/31/2017] [Indexed: 11/19/2022] Open
Abstract
In this work we determine the linear and non-linear optical properties of a Fluoro-N-Acylhydrazide derivative (FBHZ), using a combined supermolecule approach and an iterative scheme of electrostatic polarization, where the atoms of neighbouring molecules are represented by point charges. Our results for non-linear optics (NLO) are comparable to those found experimentally, suggesting that FBHZ constitutes an attractive object for future studies and for use as an interesting material for third-order NLO applications. The dynamic electrical properties of FBHZ in different solvent media are reported. Its molecular properties are closely related to supramolecular features; accordingly, we analysed all its crystal structure properties via intermolecular interactions in the solid state, using X-ray crystallography data and Hirshfeld surface (HS), including thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and hot-stage microscopy (HSM), where the results reveal crystal stability in respect to temperature variation.
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Dittrich B, Schürmann C, Hübschle CB. Invariom modeling of disordered structures: case studies on a dipeptide, an amino acid, and cefaclor, a cephalosporin antibiotic. Z KRIST-CRYST MATER 2016. [DOI: 10.1515/zkri-2016-1955] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Abstract
Routines to facilitate the treatment of disorder in invariom modeling have been implemented in the open-source program MolecoolQt, a visualization program for charge-density work, and InvariomTool, a pre-processor program. Two published structures of an amino acid and a dipeptide and the new structure of cefaclor, a cephalosporin antibiotic, provide examples with increasing amounts of disorder, which can now be successfully modeled with invarioms. Like for ordered structures, these non-spherical scattering factors predicted by density functional theory significantly improve the structural model (figures of merit and standard deviations) also in these cases. Furthermore, they allow rapid calculation and comparison of the electrostatic potential and the molecular dipole moment for the different conformers present in the crystal structures.
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Affiliation(s)
- Birger Dittrich
- Heinrich-Heine Universität Düsseldorf, Anorganische Chemie und Strukturchemie, Material- und Strukturforschung, Universitätsstraße, 1, D-40225 Düsseldorf, Germany , Tel.: +49-211-8113147
| | - Christian Schürmann
- Institut für Anorganische Chemie der Universität Göttingen, Tammannstr., 4, D-37077 Göttingen, Germany
| | - Christian B. Hübschle
- University of Bayreuth, Lehrstuhl für Kristallographie, Universitätsstraße 30, D-95440 Bayreuth, Germany
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14
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Kalaiarasi C, Pavan MS, Kumaradhas P. Topological characterization of electron density, electrostatic potential and intermolecular interactions of 2-nitroimidazole: an experimental and theoretical study. ACTA CRYSTALLOGRAPHICA SECTION B, STRUCTURAL SCIENCE, CRYSTAL ENGINEERING AND MATERIALS 2016; 72:775-786. [PMID: 27698320 DOI: 10.1107/s2052520616010581] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2016] [Accepted: 06/29/2016] [Indexed: 06/06/2023]
Abstract
An experimental charge density distribution of 2-nitroimidazole was determined from high-resolution X-ray diffraction and the Hansen-Coppens multipole model. The 2-nitroimidazole compound was crystallized and a high-angle X-ray diffraction intensity data set has been collected at low temperature (110 K). The structure was solved and further, an aspherical multipole model refinement was performed up to octapole level; the results were used to determine the structure, bond topological and electrostatic properties of the molecule. In the crystal, the molecule exhibits a planar structure and forms weak and strong intermolecular hydrogen-bonding interactions with the neighbouring molecules. The Hirshfeld surface of the molecule was plotted, which explores different types of intermolecular interactions and their strength. The topological analysis of electron density at the bond critical points (b.c.p.) of the molecule was performed, from that the electron density ρbcp(r) and the Laplacian of electron density ∇2ρbcp(r) at the b.c.p.s of the molecule have been determined; these parameters show the charge concentration/depletion of the nitroimidazole bonds in the crystal. The electrostatic parameters like atomic charges and the dipole moment of the molecule were calculated. The electrostatic potential surface of the molecule has been plotted, and it displays a large electronegative region around the nitro group. All the experimental results were compared with the corresponding theoretical calculations performed using CRYSTAL09.
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Affiliation(s)
- Chinnasamy Kalaiarasi
- Laboratory of Biocrystallography and Computational Molecular Biology, Department of Physics, Periyar University, Salem 636 011, India
| | - Mysore S Pavan
- Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore 560 012, India
| | - Poomani Kumaradhas
- Laboratory of Biocrystallography and Computational Molecular Biology, Department of Physics, Periyar University, Salem 636 011, India
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15
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Santos OL, Fonseca TL, Sabino JR, Georg HC, Castro MA. Polarization effects on the electric properties of urea and thiourea molecules in solid phase. J Chem Phys 2016; 143:234503. [PMID: 26696062 DOI: 10.1063/1.4937481] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We present theoretical results for the dipole moment, linear polarizability, and first hyperpolarizability of the urea and thiourea molecules in solid phase. The in-crystal electric properties were determined by applying a supermolecule approach in combination with an iterative electrostatic scheme, in which the surrounding molecules are represented by point charges. It is found for both urea and thiourea molecules that the influence of the polarization effects is mild for the linear polarizability, but it is marked for the dipole moment and first hyperpolarizability. The replacement of oxygen atoms by sulfur atoms increases, in general, the electric responses. Our second-order Møller-Plesset perturbation theory based iterative scheme predicts for the in-crystal dipole moment of urea and thiourea the values of 7.54 and 9.19 D which are, respectively, increased by 61% and 58%, in comparison with the corresponding isolated values. The result for urea is in agreement with the available experimental result of 6.56 D. In addition, we present an estimate of macroscopic quantities considering explicit unit cells of urea and thiourea crystals including environment polarization effects. These supermolecule calculations take into account partially the exchange and dispersion effects. The results illustrate the role played by the electrostatic interactions on the static second-order nonlinear susceptibility of the urea crystal.
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Affiliation(s)
- O L Santos
- Instituto de Física, Universidade Federal de Goiás, Campus Samambaia, 74.690-900 Goiânia, GO, Brazil
| | - T L Fonseca
- Instituto de Física, Universidade Federal de Goiás, Campus Samambaia, 74.690-900 Goiânia, GO, Brazil
| | - J R Sabino
- Instituto de Física, Universidade Federal de Goiás, Campus Samambaia, 74.690-900 Goiânia, GO, Brazil
| | - H C Georg
- Instituto de Física, Universidade Federal de Goiás, Campus Samambaia, 74.690-900 Goiânia, GO, Brazil
| | - M A Castro
- Instituto de Física, Universidade Federal de Goiás, Campus Samambaia, 74.690-900 Goiânia, GO, Brazil
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16
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Wang A, Ashurov J, Ibragimov A, Wang R, Mouhib H, Mukhamedov N, Englert U. Charge density of the biologically active molecule (2-oxo-1,3-benzoxazol-3(2H)-yl)acetic acid. ACTA CRYSTALLOGRAPHICA SECTION B, STRUCTURAL SCIENCE, CRYSTAL ENGINEERING AND MATERIALS 2016; 72:142-150. [PMID: 26830806 DOI: 10.1107/s2052520615023690] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2015] [Accepted: 12/09/2015] [Indexed: 06/05/2023]
Abstract
(2-Oxo-1,3-benzoxazol-3(2H)-yl)acetic acid is a member of a biologically active class of compounds. Its molecular structure in the crystal has been determined by X-ray diffraction, and its gas phase structure was obtained by quantum chemical calculations at the B3LYP/6-311++G(d,p) level of theory. In order to understand the dynamics of the molecule, two presumably soft degrees of freedom associated with the relative orientation of the planar benzoxazolone system and its substituent at the N atom were varied systematically. Five conformers have been identified as local minima on the resulting two-dimensional potential energy surface within an energy window of 27 kJ mol(-1). The energetically most favourable minimum closely matches the conformation observed in the crystal. Based on high-resolution diffraction data collected at low temperature, the experimental electron density of the compound was determined. Comparison with the electron density established by theory for the isolated molecule allowed the effect of intermolecular interactions to be addressed, in particular a moderately strong O-H...O hydrogen bond with a donor...acceptor distance of 2.6177 (9) Å: the oxygen acceptor is clearly polarized in the extended solid. The hydrogen bond connects consecutive molecules to chains, and the pronounced charge separation leads to stacking between neighburs with antiparallel dipole moments perpendicular to the chain direction.
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Affiliation(s)
- Ai Wang
- Institute of Inorganic Chemistry, RWTH Aachen University, Aachen, Germany
| | - Jamshid Ashurov
- Institute of Bioorganic Chemistry, Academy of Sciences of Uzbekistan, Uzbekistan
| | - Aziz Ibragimov
- Institute of General and Inorganic Chemistry, Academy of Sciences of Uzbekistan, Uzbekistan
| | - Ruimin Wang
- Institute of Inorganic Chemistry, RWTH Aachen University, Aachen, Germany
| | - Halima Mouhib
- Institute of Physical Chemistry, RWTH Aachen University, Aachen, Germany
| | - Nasir Mukhamedov
- Yunusov Institute of the Chemistry of Plant Substances, Academy of Sciences of Uzbekistan, Uzbekistan
| | - Ulli Englert
- Institute of Inorganic Chemistry, RWTH Aachen University, Aachen, Germany
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17
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Affiliation(s)
- Marta Marín-Luna
- Instituto de Química Médica (CSIC), C/Juan de la Cierva, 3, 28006-Madrid, Spain
| | - Ibon Alkorta
- Instituto de Química Médica (CSIC), C/Juan de la Cierva, 3, 28006-Madrid, Spain
| | - José Elguero
- Instituto de Química Médica (CSIC), C/Juan de la Cierva, 3, 28006-Madrid, Spain
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18
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Domagała S, Haynes DA. Experimental and theoretical charge density assessments for the 4-perfluoropyridyl- and 4-perflurophenyl-1,2,3,5-dithiadiazolyl radicals. CrystEngComm 2016. [DOI: 10.1039/c6ce01095d] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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19
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Dittrich B, Matta CF. Contributions of charge-density research to medicinal chemistry. IUCRJ 2014; 1:457-69. [PMID: 25485126 PMCID: PMC4224464 DOI: 10.1107/s2052252514018867] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/01/2014] [Accepted: 08/20/2014] [Indexed: 06/04/2023]
Abstract
This article reviews efforts in accurate experimental charge-density studies with relevance to medicinal chemistry. Initially, classical charge-density studies that measure electron density distribution via least-squares refinement of aspherical-atom population parameters are summarized. Next, interaction density is discussed as an idealized situation resembling drug-receptor interactions. Scattering-factor databases play an increasing role in charge-density research, and they can be applied both to small-molecule and macromolecular structures in refinement and analysis; software development facilitates their use. Therefore combining both of these complementary branches of X-ray crystallography is recommended, and examples are given where such a combination already proved useful. On the side of the experiment, new pixel detectors are allowing rapid measurements, thereby enabling both high-throughput small-molecule studies and macromolecular structure determination to higher resolutions. Currently, the most ambitious studies compute intermolecular interaction energies of drug-receptor complexes, and it is recommended that future studies benefit from recent method developments. Selected new developments in theoretical charge-density studies are discussed with emphasis on its symbiotic relation to crystallography.
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Affiliation(s)
- Birger Dittrich
- Institut für Anorganische und Angewandte Chemie, Martin-Luther-King-Platz 6, 20146 Hamburg, Germany
| | - Chérif F. Matta
- Department of Chemistry and Physics, Mount Saint Vincent University, Halifax, Nova Scotia B3M 2J6, Canada
- Department of Chemistry, Dalhousie University, Halifax, Nova Scotia B3H 4J3M, Canada
- Department of Chemistry, Saint Mary’s University, Halifax, Nova Scotia B3H 3C3, Canada
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20
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Polar Vector Property of the Stationary State of Condensed Molecular Matter. Symmetry (Basel) 2014. [DOI: 10.3390/sym6040844] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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21
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Farrugia LJ. Accurate H-atom parameters from X-ray diffraction data. IUCRJ 2014; 1:265-266. [PMID: 25295168 PMCID: PMC4174869 DOI: 10.1107/s2052252514018612] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2014] [Accepted: 08/15/2014] [Indexed: 06/03/2023]
Abstract
The difficulties in defining the positions and thermal parameters for hydrogen atoms using X-ray diffraction data alone are discussed.
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Affiliation(s)
- Louis J. Farrugia
- School of Chemistry, University of Glasgow, Glasgow G12 8QQ, Scotland
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22
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Capelli SC, Bürgi HB, Dittrich B, Grabowsky S, Jayatilaka D. Hirshfeld atom refinement. IUCRJ 2014; 1:361-79. [PMID: 25295177 PMCID: PMC4174878 DOI: 10.1107/s2052252514014845] [Citation(s) in RCA: 171] [Impact Index Per Article: 17.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/02/2014] [Accepted: 06/24/2014] [Indexed: 05/20/2023]
Abstract
Hirshfeld atom refinement (HAR) is a method which determines structural parameters from single-crystal X-ray diffraction data by using an aspherical atom partitioning of tailor-made ab initio quantum mechanical molecular electron densities without any further approximation. Here the original HAR method is extended by implementing an iterative procedure of successive cycles of electron density calculations, Hirshfeld atom scattering factor calculations and structural least-squares refinements, repeated until convergence. The importance of this iterative procedure is illustrated via the example of crystalline ammonia. The new HAR method is then applied to X-ray diffraction data of the dipeptide Gly-l-Ala measured at 12, 50, 100, 150, 220 and 295 K, using Hartree-Fock and BLYP density functional theory electron densities and three different basis sets. All positions and anisotropic displacement parameters (ADPs) are freely refined without constraints or restraints - even those for hydrogen atoms. The results are systematically compared with those from neutron diffraction experiments at the temperatures 12, 50, 150 and 295 K. Although non-hydrogen-atom ADPs differ by up to three combined standard uncertainties (csu's), all other structural parameters agree within less than 2 csu's. Using our best calculations (BLYP/cc-pVTZ, recommended for organic molecules), the accuracy of determining bond lengths involving hydrogen atoms from HAR is better than 0.009 Å for temperatures of 150 K or below; for hydrogen-atom ADPs it is better than 0.006 Å(2) as judged from the mean absolute X-ray minus neutron differences. These results are among the best ever obtained. Remarkably, the precision of determining bond lengths and ADPs for the hydrogen atoms from the HAR procedure is comparable with that from the neutron measurements - an outcome which is obtained with a routinely achievable resolution of the X-ray data of 0.65 Å.
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Affiliation(s)
- Silvia C. Capelli
- Department of Chemistry, University of Milan, Via Golgi 19, 20133 Milan, Italy
| | - Hans-Beat Bürgi
- Department of Chemistry and Biochemistry, Universität Bern, Freiestrasse 3, 3012 Bern, Switzerland
- Department of Chemistry, Universität Zürich, Winterthurstrasse 190, 8057 Zürich, Switzerland
| | - Birger Dittrich
- Institut für Anorganische und Angewandte Chemie, Universität Hamburg, Martin-Luther-King-Platz 6, 20146 Hamburg, Germany
- Institut für Anorganische Chemie, Georg-August-Universität Göttingen, Tammannstr. 4, 37077 Göttingen, Germany
| | - Simon Grabowsky
- School of Chemistry and Biochemistry, The University of Western Australia, 35 Stirling Highway, Crawley WA 6009, Australia
| | - Dylan Jayatilaka
- School of Chemistry and Biochemistry, The University of Western Australia, 35 Stirling Highway, Crawley WA 6009, Australia
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23
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Ahmed M, Yar M, Nassour A, Guillot B, Lecomte C, Jelsch C. Experimental and Theoretical Charge Density Analysis of a Bromoethyl Sulfonium Salt. J Phys Chem A 2013; 117:14267-75. [DOI: 10.1021/jp410301d] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Maqsood Ahmed
- CRM2,
CNRS-Institut Jean Barriol, Université de Lorraine, Vandoeuvre-lès-Nancy, France
- Department
of Chemistry, The Islamia University of Bahawalpur, Bahawalpur, Punjab, Pakistan
| | - Muhammad Yar
- Interdisciplinary
Research Center in Biomedical Materials, COMSATS Institute of Information Technology, 54000, Lahore, Pakistan
| | - Ayoub Nassour
- CRM2,
CNRS-Institut Jean Barriol, Université de Lorraine, Vandoeuvre-lès-Nancy, France
| | - Benoit Guillot
- CRM2,
CNRS-Institut Jean Barriol, Université de Lorraine, Vandoeuvre-lès-Nancy, France
| | - Claude Lecomte
- CRM2,
CNRS-Institut Jean Barriol, Université de Lorraine, Vandoeuvre-lès-Nancy, France
| | - Christian Jelsch
- CRM2,
CNRS-Institut Jean Barriol, Université de Lorraine, Vandoeuvre-lès-Nancy, France
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24
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Grabowsky S, Jayatilaka D, Fink RF, Schirmeister T, Engels B. Can Experimental Electron-Density Studies be Used as a Tool to Predict Biologically Relevant Properties of Low-Molecular Weight Enzyme Ligands? Z Anorg Allg Chem 2013. [DOI: 10.1002/zaac.201200518] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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25
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Dittrich B, Hübschle CB, Pröpper K, Dietrich F, Stolper T, Holstein J. The generalized invariom database (GID). ACTA CRYSTALLOGRAPHICA SECTION B: STRUCTURAL SCIENCE 2013. [DOI: 10.1107/s0108768113002280] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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26
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Bibila Mayaya Bisseyou Y, Bouhmaida N, Guillot B, Lecomte C, Lugan N, Ghermani N, Jelsch C. Experimental and database-transferred electron-density analysis and evaluation of electrostatic forces in coumarin-102 dye. ACTA CRYSTALLOGRAPHICA SECTION B: STRUCTURAL SCIENCE 2012; 68:646-60. [PMID: 23165601 DOI: 10.1107/s0108768112042826] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2012] [Accepted: 10/12/2012] [Indexed: 11/10/2022]
Abstract
The electron-density distribution of a new crystal form of coumarin-102, a laser dye, has been investigated using the Hansen-Coppens multipolar atom model. The charge density was refined versus high-resolution X-ray diffraction data collected at 100 K and was also constructed by transferring the charge density from the Experimental Library of Multipolar Atom Model (ELMAM2). The topology of the refined charge density has been analysed within the Bader `Atoms In Molecules' theory framework. Deformation electron-density peak heights and topological features indicate that the chromen-2-one ring system has a delocalized π-electron cloud in resonance with the N (amino) atom. The molecular electrostatic potential was estimated from both experimental and transferred multipolar models; it reveals an asymmetric character of the charge distribution across the molecule. This polarization effect is due to a substantial charge delocalization within the molecule. The molecular dipole moments derived from the experimental and transferred multipolar models are also compared with the liquid and gas-phase dipole moments. The substantial molecular dipole moment enhancements observed in the crystal environment originate from the crystal field and from intermolecular charge transfer induced and controlled by C-H···O and C-H···N intermolecular hydrogen bonds. The atomic forces were integrated over the atomic basins and compared for the two electron-density models.
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Affiliation(s)
- Yvon Bibila Mayaya Bisseyou
- Laboratoire de Cristallographie, Résonance Magnétique et Modélisations (CRM²), CNRS, UMR 7036, Institut Jean Barriol, Faculté des Sciences et Technologies, Université de Lorraine, BP 70239, 54506 Vandoeuvre-lès-Nancy CEDEX, France
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27
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Poulain-Paul A, Nassour A, Jelsch C, Guillot B, Kubicki M, Lecomte C. A critical analysis of dipole-moment calculations as obtained from experimental and theoretical structure factors. Acta Crystallogr A 2012; 68:715-28. [DOI: 10.1107/s0108767312034010] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2012] [Accepted: 07/30/2012] [Indexed: 05/26/2023] Open
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28
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Gordesli FP, Abu-Lail NI. Combined Poisson and soft-particle DLVO analysis of the specific and nonspecific adhesion forces measured between L. monocytogenes grown at various temperatures and silicon nitride. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2012; 46:10089-10098. [PMID: 22917240 DOI: 10.1021/es300653w] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Adhesion forces between pathogenic L. monocytogenes EGDe and silicon nitride (Si(3)N(4)) were measured using atomic force microscopy (AFM) under water and at room temperature for cells grown at five different temperatures (10, 20, 30, 37, and 40 °C). Adhesion forces were then decoupled into specific (hydrogen bonding) and nonspecific (electrostatic and Lifshitz-van der Waals) force components using Poisson statistical analysis. The strongest specific and nonspecific attraction forces were observed for cells grown at 30 °C, compared to those observed for cells grown at higher or lower temperatures, respectively. By combining the results of Poisson analysis with the results obtained through soft-particle Derjaguin-Landau-Verwey-Overbeek (DLVO) analysis, the contributions of the Lifshitz-van der Waals and electrostatic forces to the overall nonspecific interaction forces were determined. Our results showed that the Lifshitz-van der Waals attraction forces dominated the total nonspecific adhesion forces for all investigated thermal conditions. However, irrespective of the temperature of growth investigated, hydrogen bonding forces were always stronger than the nonspecific forces. Finally, by combining Poisson analysis with soft-particle analysis of DLVO forces, the closest separation distances where the irreversible bacterial adhesion takes place can be determined relatively easily. For all investigated thermal conditions, the closest separation distances were <1 nm.
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Affiliation(s)
- F Pinar Gordesli
- Gene and Linda Voiland School of Chemical Engineering and Bioengineering, Washington State University, Pullman, Washington 99164-2710, United States
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29
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Schürmann CJ, Pröpper K, Wagner T, Dittrich B. Invariom modeling of ceftazidime pentahydrate: molecular properties from a 200 second synchrotron microcrystal experiment. ACTA CRYSTALLOGRAPHICA SECTION B: STRUCTURAL SCIENCE 2012; 68:313-7. [PMID: 22610682 DOI: 10.1107/s0108768112017831] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2011] [Accepted: 04/21/2012] [Indexed: 11/10/2022]
Abstract
The structure of ceftazidime pentahydrate, a third generation cephalosporin antibiotic, is reported. Data collection was carried out in a remarkably short time with synchrotron radiation and the latest detector technology, illustrating that single-crystal X-ray diffraction can be used as a technique for screening hundreds of compounds in a short amount of time. Structure refinement made use of invarioms, namely non-spherical scattering factors, which allow more information to be derived from a diffraction experiment. Properties that can be screened are bond-topological parameters, empirical hydrogen-bond energies, molecular dipole moments and electrostatic potentials.
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Affiliation(s)
- C J Schürmann
- Institut für Anorganische Chemie der Universität Göttingen, Göttingen, Germany
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30
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Domagała S, Fournier B, Liebschner D, Guillot B, Jelsch C. An improved experimental databank of transferable multipolar atom models--ELMAM2. Construction details and applications. Acta Crystallogr A 2012; 68:337-51. [PMID: 22514066 DOI: 10.1107/s0108767312008197] [Citation(s) in RCA: 103] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2011] [Accepted: 02/23/2012] [Indexed: 11/10/2022] Open
Abstract
ELMAM2 is a generalized and improved library of experimentally derived multipolar atom types. The previously published ELMAM database is restricted mostly to protein atoms. The current database is extended to common functional groups encountered in organic molecules and is based on optimized local axes systems taking into account the local pseudosymmetry of the molecular fragment. In this approach, the symmetry-restricted multipoles have zero populations, while others take generally significant values. The various applications of the database are described. The deformation electron densities, electrostatic potentials and interaction energies calculated for several tripeptides and aromatic molecules are calculated using ELMAM2 electron-density parameters and compared with the former ELMAM database and density functional theory calculations.
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Affiliation(s)
- Sławomir Domagała
- Laboratoire de Cristallographie, Résonance Magnétique et Modélisations (CRM2), CNRS, UMR 7036, Institut Jean Barriol, Faculté des Sciences et Technologies, Nancy Université, BP 70239, 54506 Vandoeuvre-lès-Nancy Cedex, France
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31
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Dittrich B, Jayatilaka D. Reliable Measurements of Dipole Moments from Single-Crystal Diffraction Data and Assessment of an In-Crystal Enhancement. ELECTRON DENSITY AND CHEMICAL BONDING II 2012. [DOI: 10.1007/430_2012_78] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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32
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Paul A, Kubicki M, Kubas A, Jelsch C, Fink K, Lecomte C. Charge Density Analysis of 2-Methyl-4-nitro-1-phenyl-1H-imidazole-5-carbonitrile: An Experimental and Theoretical Study of C≡N···C≡N Interactions. J Phys Chem A 2011; 115:12941-52. [DOI: 10.1021/jp204067z] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Affiliation(s)
- Agnieszka Paul
- Faculty of Chemistry, Adam Mickiewicz University, Grunwaldzka 6, 60-780 Poznań, Poland
- Crystallographie, Résonance Magnétique et Modelisations, CRM2, UMR UHP-CNRS 7036, Institut Jean Barriol, Nancy Université, BP 70239, 54506 Vandoeuvre-les-Nancy, France
| | - Maciej Kubicki
- Faculty of Chemistry, Adam Mickiewicz University, Grunwaldzka 6, 60-780 Poznań, Poland
| | - Adam Kubas
- Karlsruhe Institute of Technology, Institute of Nanotechnology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
| | - Christian Jelsch
- Crystallographie, Résonance Magnétique et Modelisations, CRM2, UMR UHP-CNRS 7036, Institut Jean Barriol, Nancy Université, BP 70239, 54506 Vandoeuvre-les-Nancy, France
| | - Karin Fink
- Karlsruhe Institute of Technology, Institute of Nanotechnology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
| | - Claude Lecomte
- Crystallographie, Résonance Magnétique et Modelisations, CRM2, UMR UHP-CNRS 7036, Institut Jean Barriol, Nancy Université, BP 70239, 54506 Vandoeuvre-les-Nancy, France
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33
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Mata I, Molins E, Alkorta I, Espinosa E. Tuning the Interaction Energy of Hydrogen Bonds: The Effect of the Substituent. J Phys Chem A 2011; 115:12561-71. [DOI: 10.1021/jp202917z] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Ignasi Mata
- Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus UAB, 08193 Bellaterra, Spain
| | - Elies Molins
- Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus UAB, 08193 Bellaterra, Spain
| | - Ibon Alkorta
- Instituto de Química Médica (IQM-CSIC), Juan de la Cierva, 3, 28006 Madrid, Spain
| | - Enrique Espinosa
- Laboratorie de Cristallographie, Résonance Magnétique et Modélisations, CRM2, UMR CNRS 7036, Institut Jean Barriol, Nancy-Université, BP 70239, 54506 Vandoeuvre-lès-Nancy, France
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Lomize AL, Pogozheva I, Mosberg HI. Anisotropic solvent model of the lipid bilayer. 1. Parameterization of long-range electrostatics and first solvation shell effects. J Chem Inf Model 2011; 51:918-29. [PMID: 21438609 PMCID: PMC3089899 DOI: 10.1021/ci2000192] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A new implicit solvation model was developed for calculating free energies of transfer of molecules from water to any solvent with defined bulk properties. The transfer energy was calculated as a sum of the first solvation shell energy and the long-range electrostatic contribution. The first term was proportional to solvent accessible surface area and solvation parameters (σ(i)) for different atom types. The electrostatic term was computed as a product of group dipole moments and dipolar solvation parameter (η) for neutral molecules or using a modified Born equation for ions. The regression coefficients in linear dependencies of solvation parameters σ(i) and η on dielectric constant, solvatochromic polarizability parameter π*, and hydrogen-bonding donor and acceptor capacities of solvents were optimized using 1269 experimental transfer energies from 19 organic solvents to water. The root-mean-square errors for neutral compounds and ions were 0.82 and 1.61 kcal/mol, respectively. Quantification of energy components demonstrates the dominant roles of hydrophobic effect for nonpolar atoms and of hydrogen-bonding for polar atoms. The estimated first solvation shell energy outweighs the long-range electrostatics for most compounds including ions. The simplicity and computational efficiency of the model allows its application for modeling of macromolecules in anisotropic environments, such as biological membranes.
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Affiliation(s)
- Andrei L. Lomize
- Department of Medicinal Chemistry, College of Pharmacy, University of Michigan, 428 Church St., Ann Arbor, MI, 48109-1065, USA
| | - Irina Pogozheva
- Department of Medicinal Chemistry, College of Pharmacy, University of Michigan, 428 Church St., Ann Arbor, MI, 48109-1065, USA
| | - Henry I Mosberg
- Department of Medicinal Chemistry, College of Pharmacy, University of Michigan, 428 Church St., Ann Arbor, MI, 48109-1065, USA
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Lomize AL, Pogozheva ID, Mosberg HI. Anisotropic solvent model of the lipid bilayer. 2. Energetics of insertion of small molecules, peptides, and proteins in membranes. J Chem Inf Model 2011; 51:930-46. [PMID: 21438606 DOI: 10.1021/ci200020k] [Citation(s) in RCA: 119] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
A new computational approach to calculating binding energies and spatial positions of small molecules, peptides, and proteins in the lipid bilayer has been developed. The method combines an anisotropic solvent representation of the lipid bilayer and universal solvation model, which predicts transfer energies of molecules from water to an arbitrary medium with defined polarity properties. The universal solvation model accounts for hydrophobic, van der Waals, hydrogen-bonding, and electrostatic solute-solvent interactions. The lipid bilayer is represented as a fluid anisotropic environment described by profiles of dielectric constant (ε), solvatochromic dipolarity parameter (π*), and hydrogen bonding acidity and basicity parameters (α and β). The polarity profiles were calculated using published distributions of quasi-molecular segments of lipids determined by neutron and X-ray scattering for DOPC bilayer and spin-labeling data that define concentration of water in the lipid acyl chain region. The model also accounts for the preferential solvation of charges and polar groups by water and includes the effect of the hydrophobic mismatch for transmembrane proteins. The method was tested on calculations of binding energies and preferential positions in membranes for small-molecules, peptides and peripheral membrane proteins that have been experimentally studied. The new theoretical approach was implemented in a new version (2.0) of our PPM program and applied for the large-scale calculations of spatial positions in membranes of more than 1000 peripheral and integral proteins. The results of calculations are deposited in the updated OPM database ( http://opm.phar.umich.edu ).
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Affiliation(s)
- Andrei L Lomize
- Department of Medicinal Chemistry, College of Pharmacy, University of Michigan , 428 Church St., Ann Arbor, Michigan 48109-1065, USA.
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Fonseca TL, Sabino JR, Castro MA, Georg HC. A theoretical investigation of electric properties of L-arginine phosphate monohydrate including environment polarization effects. J Chem Phys 2011; 133:144103. [PMID: 20949983 DOI: 10.1063/1.3501237] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The dipole moment (μ), linear polarizability (α), and first hyperpolarizability (β(tot)) of the asymmetric unit of L-arginine phosphate (LAP) monohydrate crystal are investigated using the supermolecule approach in combination with an iterative electrostatic polarization scheme. Environment polarization effects are attained by assuring the convergence of the dipole moment of LAP embedded in the polarization field of the surrounding molecules whose atomic sites are treated as point charges. The results obtained show that in the presence of the embedding charges, the value of μ is increased by 9% but the static values of α and β(tot) are decreased, respectively, by 3% and 13%, as compared with the isolated situation. The MP2/6-311+G(d) model predicts for the in-crystal dipole moment the converged value of 33 D, in good concordance with the available experimental result of 32 D. Our estimates for the converged results of α and β(tot) are, respectively, 22.51×10(-24) and 5.01×10(-30) esu. Dispersion effects are found to have a small impact on the nonlinear optical responses of LAP in the visible region. In addition, MP2/6-311G results obtained for β(tot) by using isolated and embedded LAP dimers show that crystal packing effects have a significant contribution of the electrostatic interactions. Our results suggest that the role of the crystal environment is to minimize the effects of the intermolecular interactions in the electric properties. That is, μ and β(tot) gain a more additive character in the presence of the field of the embedding charges. This is specially marked for β(tot).
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Affiliation(s)
- T L Fonseca
- Instituto de Física, Universidade Federal de Goiás, CP 131, 74001-970 Goiânia, Brazil.
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Bąk JM, Domagała S, Hübschle C, Jelsch C, Dittrich B, Dominiak PM. Verification of structural and electrostatic properties obtained by the use of different pseudoatom databases. Acta Crystallogr A 2011; 67:141-53. [PMID: 21325717 DOI: 10.1107/s0108767310049731] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2010] [Accepted: 11/28/2010] [Indexed: 11/11/2022] Open
Abstract
The existing pseudoatom databases (ELMAM, Invariom, UBDB and ELMAM2) enable structure refinement to be performed with the use of aspherical scattering factors computed from the transferable aspherical atom model (TAAM) as an alternative to independent atom model refinement. In addition, electrostatic properties can be estimated with the help of the databases. The quality of the structural and electrostatic properties obtained from the individual databases was tested. On the basis of a 100 K high-resolution single-crystal X-ray diffraction experiment on L-His-L-Ala dihydrate and 23 K high-resolution data for L-Ala [Destro & Marsh (1988). J. Phys. Chem. 92, 966-973], the structural properties, electron-density distributions and molecular electrostatic potentials obtained from different TAAMs were compared to each other and to reference models. Experimental multipolar models and theoretical models refined against theoretical structure factors computed from periodic density functional theory (DFT) calculations were compared to the TAAMs in order to determine which model best describes the crystal-field effect. Unperturbed wavefunctions based on the MP2 and DFT calculations and properties obtained directly from these were used as a reference to judge how properly the databases reproduce the properties of isolated molecules. For Gly-L-His dihydrate, D,L-His and the above-mentioned two crystal structures, deviations of the molecular dipole moments and Coulombic intermolecular interaction energies from the reference values were examined. Root-mean-square deviations (RMSDs) and correlation coefficients were used as a quantitative measure of the quality of the analysed properties. TAAM refinements reproduce X-H bond lengths optimized in theoretical periodic calculations. Structural properties obtained from different database models are similar to each other. The anisotropic displacement parameters from TAAMs are similar to the results of experimental multipolar refinement; differences are about 0.5 and 2.5% for high-resolution and low-resolution data, respectively. Differences in dipole-moment magnitudes calculated from database models are about 5%, and directions differ by up to 30°. The values of electrostatic interaction energies estimated from the individual TAAMs differ greatly from each other and from the reference values. RMSDs are about 9-15 and 22-33 kJ mol(-1) for UBDB and the other database models, respectively.
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Affiliation(s)
- Joanna Maria Bąk
- Department of Chemistry, University of Warsaw, ul. Pasteura 1, 02-093 Warsaw, Poland
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Engels B, Schmidt TC, Gatti C, Schirmeister T, Fink RF. Challenging Problems in Charge Density Determination: Polar Bonds and Influence of the Environment. ELECTRON DENSITY AND CHEMICAL BONDING II 2011. [DOI: 10.1007/430_2010_36] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
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Domagała S, Munshi P, Ahmed M, Guillot B, Jelsch C. Structural analysis and multipole modelling of quercetin monohydrate – a quantitative and comparative study. ACTA CRYSTALLOGRAPHICA SECTION B: STRUCTURAL SCIENCE 2010; 67:63-78. [DOI: 10.1107/s0108768110041996] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2010] [Accepted: 10/16/2010] [Indexed: 11/11/2022]
Abstract
The multipolar atom model, constructed by transferring the charge-density parameters from an experimental or theoretical database, is considered to be an easy replacement of the widely used independent atom model. The present study on a new crystal structure of quercetin monohydrate [2-(3,4-dihydroxyphenyl)-3,5,7-trihydroxy-4H-chromen-4-one monohydrate], a plant flavonoid, determined by X-ray diffraction, demonstrates that the transferred multipolar atom model approach greatly improves several factors: the accuracy of atomic positions and the magnitudes of atomic displacement parameters, the residual electron densities and the crystallographic figures of merit. The charge-density features, topological analysis and electrostatic interaction energies obtained from the multipole models based on experimental database transfer and periodic quantum mechanical calculations are found to compare well. This quantitative and comparative study shows that in the absence of high-resolution diffraction data, the database transfer approach can be applied to the multipolar electron density features very accurately.
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Holstein JJ, Luger P, Kalinowski R, Mebs S, Paulman C, Dittrich B. Validation of experimental charge densities: refinement of the macrolide antibiotic roxithromycin. ACTA CRYSTALLOGRAPHICA SECTION B: STRUCTURAL SCIENCE 2010; 66:568-77. [DOI: 10.1107/s0108768110026480] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2009] [Accepted: 07/05/2010] [Indexed: 11/10/2022]
Abstract
Multipole refinements of larger organic molecules have so far been limited to a few exceptional cases. We report an investigation of the detailed experimental electron-density distribution (EDD) of roxithromycin, a macrolide antibiotic consisting of 134 atoms. Although the experimental multipole refinement on high-resolution synchrotron data converged smoothly, validation of the electron density by calculation of an `experiment minus invariom' difference density revealed conformational disorder of the H atoms. Hydrogen disorder is shown to affect the EDD, the electrostatic potential and atomic properties as defined by Bader's quantum theory of atoms in molecules. A procedure to obtain the electron density distribution in the presence of disorder is proposed.
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Matveev VV. Native aggregation as a cause of origin of temporary cellular structures needed for all forms of cellular activity, signaling and transformations. Theor Biol Med Model 2010; 7:19. [PMID: 20534114 PMCID: PMC2901313 DOI: 10.1186/1742-4682-7-19] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2010] [Accepted: 06/09/2010] [Indexed: 11/28/2022] Open
Abstract
According to the hypothesis explored in this paper, native aggregation is genetically controlled (programmed) reversible aggregation that occurs when interacting proteins form new temporary structures through highly specific interactions. It is assumed that Anfinsen's dogma may be extended to protein aggregation: composition and amino acid sequence determine not only the secondary and tertiary structure of single protein, but also the structure of protein aggregates (associates). Cell function is considered as a transition between two states (two states model), the resting state and state of activity (this applies to the cell as a whole and to its individual structures). In the resting state, the key proteins are found in the following inactive forms: natively unfolded and globular. When the cell is activated, secondary structures appear in natively unfolded proteins (including unfolded regions in other proteins), and globular proteins begin to melt and their secondary structures become available for interaction with the secondary structures of other proteins. These temporary secondary structures provide a means for highly specific interactions between proteins. As a result, native aggregation creates temporary structures necessary for cell activity. "One of the principal objects of theoretical research in any department of knowledge is to find the point of view from which the subject appears in its greatest simplicity." Josiah Willard Gibbs (1839-1903)
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Affiliation(s)
- Vladimir V Matveev
- Laboratory of Cell Physiology, Institute of Cytology, Russian Academy of Sciences, Tikhoretsky Ave 4, St, Petersburg 194064, Russia.
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Fantoni AC, Pozzi CG, Punte G. On the Electron Density Topology and Electrostatic Properties of Nitroanilines. A Theoretical Investigation on m-Nitroaniline and 2-Methyl-5-nitroaniline Crystals. J Phys Chem A 2009; 113:9527-32. [DOI: 10.1021/jp904318q] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Adolfo C. Fantoni
- IFLP (CCT-La Plata), Departamento de Física, Facultad de Ciencias Exactas, UNLP CC 67, 1900 La Plata, Argentina
| | - C. Gustavo Pozzi
- IFLP (CCT-La Plata), Departamento de Física, Facultad de Ciencias Exactas, UNLP CC 67, 1900 La Plata, Argentina
| | - Graciela Punte
- IFLP (CCT-La Plata), Departamento de Física, Facultad de Ciencias Exactas, UNLP CC 67, 1900 La Plata, Argentina
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Mladenovic M, Arnone M, Fink RF, Engels B. Environmental effects on charge densities of biologically active molecules: do molecule crystal environments indeed approximate protein surroundings? J Phys Chem B 2009; 113:5072-82. [PMID: 19320453 DOI: 10.1021/jp809537v] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In the present paper, we investigate whether crystal and enzyme environments influence the electron density (ED) of active compounds in a similar manner. This supposition is essential for high-resolution X-ray studies, which use the EDs obtained from crystals of the pure active compound as approximations for the ED of the active compound in its complex with the target enzyme. The EDs of such complexes determine the molecular recognition process between the targeted enzyme and active compound and are, hence, extremely useful tools for rational drug design. The approximation of such EDs by data obtained from crystals of the pure active compound is needed since high-resolution X-ray experiments of the target-ligand complexes are still extremely demanding. Quantum mechanical/molecular mechanical (QM/MM) and pure QM calculations are employed to determine the EDs of two inhibitors, the reversible trans-4-(aminomethyl)cyclohexane-1-carboxylic acid (AMCHA) and the irreversible E64c in four different environments (the enzyme-inhibitor complex, crystals of the pure compounds, a continuum solvation model, and the gas phase). Our investigation shows that the environment inside of the crystal of the pure active compound generally influences the ED of an active compound in a very similar way as the enzyme surrounding in the complex between the active compound and target enzyme. However, this does not hold any more if the geometrical arrangement of the inhibitor in the enzyme differs significantly from that in the crystal. While EDs computed for gas-phase environments deviate strongly from those in crystal and protein surroundings, polar solvent environments provide rather similar electron distributions. Thus, such continuum solvation models are very well suited to compute density databases which are to be employed for the determination of the ED of macromolecules.
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Affiliation(s)
- Milena Mladenovic
- Institut fur Organische Chemie, Universitat Wurzburg, Am Hubland, D-97074 Wurzburg, Germany
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Jayatilaka D, Munshi P, Turner MJ, Howard JAK, Spackman MA. Refractive indices for molecular crystals from the response of X-ray constrained Hartree-Fock wavefunctions. Phys Chem Chem Phys 2009; 11:7209-18. [PMID: 19672531 DOI: 10.1039/b906072c] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Refractive indices for molecular crystals are obtained from Hartree-Fock wavefunctions constrained to reproduce a set of experimental X-ray structure factors. Coupled-perturbed Hartree-Fock theory is used to calculate the in-crystal effective polarizabilities from which the refractive indices are obtained, thus eliminating the need for the calibration procedure used in earlier work by Whitten et al. [J. Chem. Phys. 2006, 125, 174505]. The results clearly demonstrate that these X-ray constrained Hartree-Fock (XCHF) wavefunctions reflect genuine effects of intermolecular interactions in crystals. Molecular dipole moments are consistently in excellent agreement with ab initio MP2 estimates that incorporate the effects of the crystal field. Consistent agreement of the XCHF refractive indices with experimental measurements at optical frequencies confirms that this approach can provide both meaningful results and considerable insight into the relative importance of molecular properties and crystal field effects in determining the detailed nature of the refractivity tensor.
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Affiliation(s)
- Dylan Jayatilaka
- Chemistry-M313, School of Biomedical, Biomolecular & Chemical Sciences, University of Western Australia, Crawley WA, Australia.
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Charge density analysis of two proton transfer complexes: Understanding hydrogen bonding and determination of in-crystal dipole moments. J CHEM SCI 2009. [DOI: 10.1007/s12039-008-0093-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Cooper TG, Hejczyk KE, Jones W, Day GM. Molecular Polarization Effects on the Relative Energies of the Real and Putative Crystal Structures of Valine. J Chem Theory Comput 2008; 4:1795-805. [DOI: 10.1021/ct800195g] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Timothy G. Cooper
- The Pfizer Institute for Pharmaceutical Materials Science, Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom
| | - Katarzyna E. Hejczyk
- The Pfizer Institute for Pharmaceutical Materials Science, Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom
| | - William Jones
- The Pfizer Institute for Pharmaceutical Materials Science, Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom
| | - Graeme M. Day
- The Pfizer Institute for Pharmaceutical Materials Science, Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom
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