ORCID Profile
0000-0003-3552-8625
Current Organisation
Aarhus Universitet
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Structural Chemistry and Spectroscopy | Physical Chemistry of Materials | Solid State Chemistry | Physical Chemistry (Incl. Structural)
Expanding Knowledge in the Chemical Sciences | Expanding Knowledge in the Physical Sciences | Human Pharmaceutical Products not elsewhere classified |
Publisher: American Chemical Society (ACS)
Date: 23-01-2014
DOI: 10.1021/CG401069Y
Publisher: Wiley
Date: 14-03-2019
Abstract: There are many ex les of atoms in molecules that violate Lewis' octet rule, because they have more than four electron pairs assigned to their valence. These atoms are referred to as hypervalent. However, hypervalency may be regarded as an artifact arising from Lewis' description of molecules, which is based on the assumption that electrons are localized in two-center two-electron bonds and lone pairs. In the present paper, the isoelectronic phosphate (PO
Publisher: Wiley
Date: 02-12-2021
Abstract: This review presents a critical and comprehensive overview of current experimental measurements of complete elastic constant tensors for molecular crystals. For a large fraction of these molecular crystals, detailed comparisons are made with elastic tensors obtained using the corrected small basis set Hartree–Fock method S‐HF‐3c, and these are shown to be competitive with many of those obtained from more sophisticated density functional theory plus dispersion (DFT‐D) approaches. These detailed comparisons between S‐HF‐3c, experimental and DFT‐D computed tensors make use of a novel rotation‐invariant spherical harmonic description of the Young's modulus, and identify outliers among sets of independent experimental results. The result is a curated database of experimental elastic tensors for molecular crystals, which we hope will stimulate more extensive use of elastic tensor information—experimental and computational—in studies aimed at correlating mechanical properties of molecular crystals with their underlying crystal structure.
Publisher: American Chemical Society (ACS)
Date: 14-02-2019
DOI: 10.1021/JACS.8B12927
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
Publisher: Royal Society of Chemistry (RSC)
Date: 2021
DOI: 10.1039/D1SC03714E
Abstract: Multicomponent molecular alloy crystals exhibit intriguing effects of tuning and quenching in their photoluminescence, suggesting ‘alloy-crystal engineering’ as a useful design strategy for molecular functional materials.
Publisher: Elsevier BV
Date: 2013
Publisher: Wiley
Date: 08-01-2015
Publisher: CSIRO Publishing
Date: 2018
DOI: 10.1071/CH17620
Abstract: The remarkable structural ersity observed in polymorphs of 5-methyl-2-[(2-nitrophenyl)amino]-3-thiophenecarbonitrile (commonly known as ROY) challenges computational attempts to predict or rationalize their relative stability. This modest study explores the applicability of CE-B3LYP model energy calculation of lattice energies (using experimental crystal structures), supplemented by a systematic approach to account for conformational energy differences. The CE-B3LYP model provides sensible estimates of absolute and relative lattice energies for the polymorphs, provided care is taken to achieve convergence in the summation of pairwise terms. Conformational energy differences based on density functional theory (DFT) energies are shown to be unreliable, but MP2 energies based on DFT-optimized structures show considerable promise.
Publisher: Wiley
Date: 24-06-2019
Abstract: The observation of an unusual crystal habit in the common diuretic drug hydrochlorothiazide (HCT), and identification of its subtle conformational chirality, has stimulated a detailed investigation of its crystalline forms. Enantiomeric conformers of HCT resolve into an unusual structure of conjoined enantiomorphic twin crystals comprising enantiopure domains of opposite chirality. The purity of the domains and the chiral molecular conformation are confirmed by spatially revolved synchrotron micro-XRD experiments and neutron diffraction, respectively. Macroscopic inversion twin symmetry observed between the crystal wings suggests a pseudoracemic structure that is not a solid solution or a layered crystal structure, but an unusual structural variant of conglomerates and racemic twins. Computed interaction energies for molecular pairs in the racemic and enantiopure polymorphs of HCT, and the observation of large opposing unit-cell dipole moments for the enantiopure domains in these twin crystals, suggest a plausible crystal nucleation mechanism for this unusual crystal habit.
Publisher: Wiley
Date: 06-02-2019
Abstract: Classical ex les of supramolecular recognition units or synthons are the ones formed by hydrogen bonds. Here, we report the ubiquity of a S⋅⋅⋅O chalcogen bonded synthon observed in a series of supramolecular complexes of the amyotrophic lateral sclerosis drug riluzole. Although the potential of higher chalcogens such as Se and Te to form robust and directional chalcogen bonded motifs is known, intermolecular sulfur chalcogen bonding is considered to be weak owing to the lower polarizability of S atoms. Here, the robustness and electronic nature of a S⋅⋅⋅O chalcogen bonding non-classical synthon, and the origin of its exceptional directionality have been explored. Bond orders of the drug-coformer chalcogen bonding are found to be as high as one third of a single bond, and they are largely ionic in nature. The contribution of the S⋅⋅⋅O chalcogen bonded motifs to the lattice energies of a series of crystals from the Cambridge Structural Database has been analyzed, showing they can be indeed significant, especially in molecules devoid of strong hydrogen bond donor groups.
Publisher: Wiley
Date: 28-09-2023
Publisher: Royal Society of Chemistry (RSC)
Date: 2015
DOI: 10.1039/C5CP04412J
Abstract: Experimental charge density analysis combined with the quantum crystallographic technique of X-ray wavefunction refinement (XWR) provides quantitative insights into the intra- and intermolecular interactions formed by acetazolamide, a diuretic drug.
Publisher: Wiley
Date: 04-05-2017
Publisher: Royal Society of Chemistry (RSC)
Date: 2012
DOI: 10.1039/C2CC34912D
Abstract: Crystal structures of polymorphs and solvatomorphs of the potential anxiolytic drug fenobam exhibit an exclusive preference for one of the two possible tautomeric structures. A novel methodology based on nonlinear optical response has been successfully employed to detect the presence of a polymorphic impurity in a mixture of polymorphs.
Publisher: Royal Society of Chemistry (RSC)
Date: 2022
DOI: 10.1039/D2CE00700B
Abstract: A detailed structural analysis of a series of α-hydroxy ketone derivatives in terms of lattice energies and conformational energies reveals the competing factors of inter- and intramolecular interactions that direct conformational preferences.
Publisher: American Chemical Society (ACS)
Date: 26-06-2012
DOI: 10.1021/CG300704B
Publisher: Royal Society of Chemistry (RSC)
Date: 2023
DOI: 10.1039/D3RA04709A
Abstract: A novel [(3,5-lutidine) 2 Co(OAc) 2 (H 2 O) 2 ] complex (1) shows impressive OER activity, two and half times higher than that of a state-of-the-art IrO 2 catalyst.
Publisher: Wiley
Date: 19-08-2019
Abstract: Most structure-based drug discovery methods utilize crystal structures of receptor proteins. Crystal engineering, on the other hand, utilizes the wealth of chemical information inherent in small-molecule crystal structures in the Cambridge Structural Database (CSD). We show that the interaction surfaces and shapes of molecules in experimentally determined small-molecule crystal structures can serve as effective tools in drug discovery. Our description of the shape and interaction propensities of molecules in their crystal structures can be used to screen them for specific binding compatibility with protein targets, as demonstrated through the high-throughput profiling of around 138 000 small-molecule structures in the CSD and a series of drug-protein crystal structures. Electron-density-based intermolecular boundary surfaces in small-molecule crystal structures and in target-protein pockets are utilized to identify potential ligand molecules from the CSD based on 3D shape and intermolecular interaction matching.
Publisher: American Chemical Society (ACS)
Date: 05-11-2015
Publisher: American Chemical Society (ACS)
Date: 06-02-2018
Abstract: Using four different benchmark sets of molecular crystals, we establish the level of confidence for lattice energies estimated using CE-B3LYP model energies and experimental crystal structures. [ IUCrJ 2017 , 4 , 575 - 587 10.1107/S205225251700848X .] We conclude that they compare very well with available benchmark estimates derived from sublimation enthalpies, and in many cases they are comparable with, and sometimes better than, more computationally demanding approaches, such as those based on periodic DFT plus dispersion methodologies. The performance over the complete set of 110 crystals indicates a mean absolute deviation from benchmark energies of only 6.6 kJ mol
Publisher: Elsevier BV
Date: 03-2021
Publisher: Wiley
Date: 25-11-2021
Abstract: This review presents a critical and comprehensive overview of current experimental measurements of complete elastic constant tensors for molecular crystals. For a large fraction of these molecular crystals, detailed comparisons are made with elastic tensors obtained using the corrected small basis set Hartree–Fock method S‐HF‐3c, and these are shown to be competitive with many of those obtained from more sophisticated density functional theory plus dispersion (DFT‐D) approaches. These detailed comparisons between S‐HF‐3c, experimental and DFT‐D computed tensors make use of a novel rotation‐invariant spherical harmonic description of the Young's modulus, and identify outliers among sets of independent experimental results. The result is a curated database of experimental elastic tensors for molecular crystals, which we hope will stimulate more extensive use of elastic tensor information—experimental and computational—in studies aimed at correlating mechanical properties of molecular crystals with their underlying crystal structure.
Publisher: American Astronomical Society
Date: 09-04-2020
Publisher: American Chemical Society (ACS)
Date: 19-03-2021
Publisher: Wiley
Date: 28-09-2023
Publisher: American Chemical Society (ACS)
Date: 21-07-2014
DOI: 10.1021/CG500043N
Publisher: Royal Society of Chemistry (RSC)
Date: 2016
DOI: 10.1039/C5CC09741J
Abstract: The polymorphs of ( Z )-2-fluoro- N ′-phenyl benzamidamide with multiple Z ′ form “equi-energetic” crystal structures and exhibit “quasi-isostructurality”.
Publisher: American Chemical Society (ACS)
Date: 28-04-2023
Publisher: Wiley
Date: 04-05-2017
Abstract: Bending in molecular crystals is typically associated with the anisotropy of intermolecular interactions. The intriguing observation is reported of plastic bending in dimethyl sulfone, which exhibits nearly isotropic crystal packing and interaction topology, defying the known structural models of bending crystals. The origin of the bending phenomenon has been explored in terms of intermolecular interaction energies, experimental X-ray charge density analysis, and variable temperature neutron diffraction studies. H⋅⋅⋅H dihydrogen interactions and differences in electrostatic complementarity between molecular layers are found to facilitate the bending behavior.
Publisher: Wiley
Date: 12-03-2015
Abstract: Structural studies on the polymorphs of the organoselenium antioxidant ebselen and its derivative show the potential of organic selenium to form unusually short Se⋅⋅⋅O chalcogen bonds that lead to conserved supramolecular recognition units. Se⋅⋅⋅O interactions observed in these polymorphs are the shortest such chalcogen bonds known for organoselenium compounds. The FTIR spectral evolution characteristics of this interaction from solution state to solid crystalline state further validates the robustness of this class of supramolecular recognition units. The strength and electronic nature of the Se⋅⋅⋅O chalcogen bonds were explored using high-resolution X-ray charge density analysis and atons-in-molecules (AIM) theoretical analysis. A charge density study unravels the strong electrostatic nature of Se⋅⋅⋅O chalcogen bonding and soft-metal-like behavior of organoselenium. An analysis of the charge density around Se-N and Se-C covalent bonds in conjunction with the Se⋅⋅⋅O chalcogen bonding modes in ebselen and its analogues provides insights into the mechanism of drug action in this class of organoselenium antioxidants. The potential role of the intermolecular Se⋅⋅⋅O chalcogen bonding in forming the intermediate supramolecular assembly that leads to the bond cleavage mechanism has been proposed in terms of electron density topological parameters in a series of molecular complexes of ebselen with reactive oxygen species (ROS).
Publisher: Royal Society of Chemistry (RSC)
Date: 2014
DOI: 10.1039/C3CC47226D
Abstract: The validity of the newly proposed 'carbon bonding', an interaction where a carbon atom acts as an electrophilic site towards a variety of nucleophiles, has been investigated in the solid state. X-ray charge density analysis provides experimental evidence for this hitherto unexplored interaction and unravels its nature and strength.
Publisher: Wiley
Date: 24-06-2019
Publisher: American Chemical Society (ACS)
Date: 20-04-2015
DOI: 10.1021/CG5016687
Publisher: Elsevier BV
Date: 08-2014
Publisher: American Chemical Society (ACS)
Date: 26-11-2012
DOI: 10.1021/CG301211H
Publisher: International Union of Crystallography (IUCr)
Date: 29-08-2018
DOI: 10.1107/S2052252518010758
Abstract: The question of whether intermolecular interactions in crystals originate from localized atom...atom interactions or as a result of holistic molecule...molecule close packing is a matter of continuing debate. In this context, the newly introduced Roby–Gould bond indices are reported for intermolecular `σ-hole' interactions, such as halogen bonding and chalcogen bonding, and compared with those for hydrogen bonds. A series of 97 crystal systems exhibiting these interaction motifs obtained from the Cambridge Structural Database (CSD) has been analysed. In contrast with conventional bond-order estimations, the new method separately estimates the ionic and covalent bond indices for atom...atom and molecule...molecule bond orders, which shed light on the nature of these interactions. A consistent trend in charge transfer from halogen/chalcogen bond-acceptor to bond-donor groups has been found in these intermolecular interaction regions via Hirshfeld atomic partitioning of the electron populations. These results, along with the `conservation of bond orders' tested in the interaction regions, establish the significant role of localized atom...atom interactions in the formation of these intermolecular binding motifs.
Publisher: Elsevier BV
Date: 04-2012
DOI: 10.1016/J.EJMECH.2012.02.026
Abstract: Four new 2-oxo-1,2-dihydrobenzo[h]quinoline-3-carbaldehyde N-substituted thiosemicarbazone ligands (H(2)-LR, where R = H, Me, Et or Ph) and their corresponding new cobalt(III) complexes have been synthesized and characterized. The structures of the complexes 2 and 3 were determined by single crystal X-ray diffraction analysis. The interactions of the new complexes with DNA were investigated by absorption, emission and viscosity studies which indicated that the complexes bind to DNA via intercalation. Antioxidant studies of the new complexes showed that the significant antioxidant activity against DPPH radical. In addition, the in vitro cytotoxicity of complexes 1-4 against A549 cell line was assayed which showed higher cytotoxic activity with lower IC(50) values indicating their efficiency in killing the cancer cells even at very low concentrations.
Publisher: Royal Society of Chemistry (RSC)
Date: 2015
DOI: 10.1039/C4CC09074H
Abstract: Energy frameworks provide an approach to understanding crystal packing by combining quantitative intermolecular interaction energies with qualitative and appealing graphics.
Publisher: International Union of Crystallography (IUCr)
Date: 13-03-2013
Publisher: American Chemical Society (ACS)
Date: 19-04-2012
DOI: 10.1021/CG3002948
Publisher: Royal Society of Chemistry (RSC)
Date: 2015
DOI: 10.1039/C5CC03322E
Abstract: The first ex les of organic alloys of two room temperature liquids, obtained and characterized via in situ cryo-crystallography, are presented. Thiophenol and selenophenol, which exhibit isostructurality and similar modes of S⋯S and Se⋯Se homo-chalcogen interactions along with weak and rare S–H⋯S and Se–H⋯Se hydrogen bonds, are shown to form solid solutions exhibiting Veggard's law-like trends.
Publisher: Wiley
Date: 19-08-2019
Publisher: American Chemical Society (ACS)
Date: 07-11-2019
DOI: 10.1021/ACS.JPCLETT.9B02734
Abstract: Hydrophobic interactions are often explored in solution-state aggregation of molecules. However, an experimental electron density description about these interactions is still lacking. Here, we report a systematic study on the electronic nature of methyl···methyl hydrophobic interactions in a series of multicomponent crystals of biologically active molecules. Charge density models based on high-resolution X-ray diffraction allow the visualization of subtle details of electron density features in the interaction region. Our study classifies these interactions as atypical group···group interactions in contrast to σ-hole interactions, which are stabilized by the minimized electrostatic repulsion and maximized dispersion forces. For the first time, we quantified the solid-state entropic contribution from the torsional mode of the methyl groups in stabilizing these interactions by thermal motion analysis based on neutron diffraction as well as variable-temperature crystallography. The carbon atoms in methyl···methyl interactions show a unique upfield chemical shift in the
Publisher: American Chemical Society (ACS)
Date: 15-05-2023
Publisher: Springer Science and Business Media LLC
Date: 24-02-2016
DOI: 10.1038/SREP22204
Abstract: Molecular shape is important in both crystallisation and supramolecular assembly, yet its role is not completely understood. We present a computationally efficient scheme to describe and classify the molecular shapes in crystals. The method involves rotation invariant description of Hirshfeld surfaces in terms of of spherical harmonic functions. Hirshfeld surfaces represent the boundaries of a molecule in the crystalline environment and are widely used to visualise and interpret crystalline interactions. The spherical harmonic description of molecular shapes are compared and classified by means of principal component analysis and cluster analysis. When applied to a series of metals, the method results in a clear classification based on their lattice type. When applied to around 300 crystal structures comprising of series of substituted benzenes, naphthalenes and phenylbenzamide it shows the capacity to classify structures based on chemical scaffolds, chemical isosterism and conformational similarity. The computational efficiency of the method is demonstrated with an application to over 14 thousand crystal structures. High throughput screening of molecular shapes and interaction surfaces in the Cambridge Structural Database (CSD) using this method has direct applications in drug discovery, supramolecular chemistry and materials design.
Start Date: 06-2021
End Date: 06-2021
Amount: $393,116.00
Funder: Australian Research Council
View Funded Activity