Posts Tagged ‘Crystal’
Thursday, June 1st, 2017
Conformational polymorphism occurs when a compound crystallises in two polymorphs differing only in the relative orientations of flexible groups (e.g. Ritonavir).[1] At the Beilstein conference, Ian Bruno mentioned another type; tautomeric polymorphism, where a compound can crystallise in two forms differing in the position of acidic protons. Here I explore three such examples.
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References
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G.J.O. Beran, I.J. Sugden, C. Greenwell, D.H. Bowskill, C.C. Pantelides, and C.S. Adjiman, "How many more polymorphs of ROY remain undiscovered", Chemical Science, vol. 13, pp. 1288-1297, 2022. http://dx.doi.org/10.1039/D1SC06074K
Tags:Chemical IT, Chemistry, chloroform solutions, Conformational isomerism, Crystal, crystallography, gas phase, Ian Bruno, Isomerism, Polymorphism, Ritonavir, S-centre, Tautomer
Posted in crystal_structure_mining | No Comments »
Saturday, April 15th, 2017
Back in the early 1990s, we first discovered the delights of searching crystal structures for unusual bonding features.[1] One of the first cases was a search for hydrogen bonds formed to the π-faces of alkenes and alkynes. In those days the CSD database of crystal structures was a lot smaller (<80,000 structures; it’s now ten times larger) and the search software less powerful. So here is an update.
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References
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H.S. Rzepa, M.H. Smith, and M.L. Webb, "A crystallographic AM1 and PM3 SCF-MO investigation of strong OH ⋯π-alkene and alkyne hydrogen bonding interactions", J. Chem. Soc., Perkin Trans. 2, pp. 703-707, 1994. http://dx.doi.org/10.1039/P29940000703
Tags:calculated energy, chemical bonding, Chemistry, Crystal, crystallography, energy, energy calculation, Intermolecular forces, Nature, search query, search software, Supramolecular chemistry
Posted in crystal_structure_mining | 2 Comments »