Chick C. Wilson

Bio: Chick C. Wilson is an academic researcher from University of Bath. The author has contributed to research in topics: Neutron diffraction & Hydrogen bond. The author has an hindex of 37, co-authored 194 publications receiving 5095 citations. Previous affiliations of Chick C. Wilson include University of Glasgow & Rutherford Appleton Laboratory.

Comparing entire crystal structures: structural genetic fingerprinting

Abstract: This paper describes a proof-of-concept example for a method that allows the calculation of a similarity index between whole molecular crystal structures; this has been termed ‘structural genetic fingerprinting’. It is based on the use of fingerprint plots derived from Hirshfeld surfaces coupled with cluster analysis and associated multivariate statistics. Using this formalism, it is possible to show quantitatively (using correlation coefficients) that, for example naphthalene is more similar to anthracene than to benzene, and moreover that benzodicoronene is more similar to anthrabenzonaphthopentacene than naphthalene is to anthracene. Whereas the correlation coefficients themselves obtained say nothing about the ways in which the patterns of intermolecular interactions are similar or different for two different structures, the fingerprint plots do contain such information. In principle this method for quantifying structural similarities of whole molecular crystal structures should be both robust and generally applicable. This method is potentially applicable to datasets consisting of many hundreds or even thousands of structures.

First O-H-N Hydrogen Bond with a Centered Proton Obtained by Thermally Induced Proton Migration.

Abstract: Within a range of 0.1 A, the H atom in the O-H-N hydrogen bond of the adduct 4-methylpyridine⋅pentachlorophenol could be shifted by a simple adjustment of temperature. At approximately 90 K the H atom is exactly centered between the O and the N atoms, as could be shown by stepwise monitoring by using variable-temperature single-crystal neutron diffraction.

SXD – the single-crystal diffractometer at the ISIS spallation neutron source

Abstract: SXD, the single-crystal diffractometer at the ISIS spallation neutron source, uses an array of two-dimensional position-sensitive detectors and the neutron time-of-flight technique to measure diffraction data throughout very large volumes of reciprocal space for each fixed orientation of a single-crystal sample. This paper describes SXD in detail, following major improvements to the instrument. Particular emphasis is placed on the range of science possible, using recent results as examples, and the opportunities for future experiments.

Crystal Engineering and Correspondence between Molecular and Crystal Structures. Are 2- and 3-Aminophenols Anomalous?

Abstract: Single-crystal neutron diffraction analyses of 2- and 3-aminophenols have been performed In addition to O−H···N and N−H···O hydrogen bonds, both these structures contain previously unidentified N−

From weak interactions to covalent bonds: A continuum in the complexes of 1,8-bis(dimethylamino)naphthalene

Abstract: Experimental charge density distributions in a series of ionic complexes of 1,8-bis(dimethylamino)naphthalene (DMAN) with four different acids: 1,2,4,5-benzenetetracarboxylic acid (pyromellitic acid), 4,5-dichlorophthalic acid, dicyanoimidazole, and o-benzoic sulfimide dihydrate (saccharin) have been analyzed. Variation of charge density properties and derived local energy densities are investigated, over all inter- and intramolecular interactions present in altogether five complexes of DMAN. All the interactions studied {[O···H···O]-, C−H···O, [N−H···N]+, O−H···O, C−H···N, Cπ···Nπ, Cπ···Cπ, C−H···Cl, N−H+ } follow exponential dependences of the electron density, local kinetic and potential energies at the bond critical points on the length of the interaction line. The local potential energy density at the bond critical points has a near-linear relationship to the electron density. There is also a Morse-like dependence of the laplacian of rho on the length of interaction line, which allows a differentiat...

The hydrogen bond in the solid state.

Abstract: The hydrogen bond is the most important of all directional intermolecular interactions. It is operative in determining molecular conformation, molecular aggregation, and the function of a vast number of chemical systems ranging from inorganic to biological. Research into hydrogen bonds experienced a stagnant period in the 1980s, but re-opened around 1990, and has been in rapid development since then. In terms of modern concepts, the hydrogen bond is understood as a very broad phenomenon, and it is accepted that there are open borders to other effects. There are dozens of different types of X-H.A hydrogen bonds that occur commonly in the condensed phases, and in addition there are innumerable less common ones. Dissociation energies span more than two orders of magnitude (about 0.2-40 kcal mol(-1)). Within this range, the nature of the interaction is not constant, but its electrostatic, covalent, and dispersion contributions vary in their relative weights. The hydrogen bond has broad transition regions that merge continuously with the covalent bond, the van der Waals interaction, the ionic interaction, and also the cation-pi interaction. All hydrogen bonds can be considered as incipient proton transfer reactions, and for strong hydrogen bonds, this reaction can be in a very advanced state. In this review, a coherent survey is given on all these matters.

Hirshfeld surface analysis

Abstract: In the last few years the analysis of molecular crystal structures using tools based on Hirshfeld surfaces has rapidly gained in popularity. This approach represents an attempt to venture beyond the current paradigm—internuclear distances and angles, crystal packing diagrams with molecules represented via various models, and the identification of close contacts deemed to be important—and to view molecules as “organic wholes”, thereby fundamentally altering the discussion of intermolecular interactions through an unbiased identification of all close contacts.

Fingerprinting intermolecular interactions in molecular crystals

Abstract: We have recently described a remarkable new way of exploring packing modes and intermolecular interactions in molecular crystals using a novel partitioning of crystal space. These molecular Hirshfeld surfaces reflect intermolecular interactions in a novel visual manner, offering a hitherto unseen picture of molecular shape in a crystalline environment. The surfaces encode information about all intermolecular interactions simultaneously, but sophisticated interactive graphics are required in order to extract the information most efficiently. To overcome this we have devised a two-dimensional mapping which summarizes quantitatively the nature and type of intermolecular interaction experienced by a molecule in the bulk, and presents it in a convenient graphical format. The mapping takes advantage of the triangulation of the Hirshfeld surfaces, and plots the fraction of points on the surface as a function of the closest distances from the point to nuclei inside and outside the surface. In this manner all interaction types (for example, hydrogen bonding, close and distant van der Waals contacts, C–H⋯π interactions, π–π stacking) are readily identifiable, and it becomes a straightforward matter to classify molecular crystals by the nature of interactions, and to rapidly identify similarities and differences which can become obscured when examining crystal packing diagrams. These plots are a novel visual representation of all the intermolecular interactions simultaneously, and are unique for a given crystal structure and polymorph. Applications to a wide variety of molecular crystals and intermolecular interactions are presented, including polymorphic systems, as well as crystals where Z′ > 1.