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Milngavie, United Kingdom

Warzecha M.,University of West of Scotland | Calvo-Castro J.,University of West of Scotland | Kennedy A.R.,University of Strathclyde | Macpherson A.N.,University of Manchester | And 4 more authors.
Chemical Communications | Year: 2014

Sensitive optical detection of nitroaromatic vapours with diketopyrrolopyrrole thin films is reported for the first time and the impact of thin film crystal structure and morphology on fluorescence quenching behaviour demonstrated. This journal is © The Royal Society of Chemistry. Source

Buist A.R.,University of Strathclyde | Kennedy A.R.,University of Strathclyde | Shankland K.,University of Reading | Shankland N.,Crystallografx Ltd. | Spillman M.J.,University of Reading
Crystal Growth and Design | Year: 2013

In situ generation of HCl or HBr in alcohol leads to O-protonation of the amide group of carbamazepine. Six salt phases have been produced using this method and their crystal structures determined by single crystal diffraction. A new polymorph of carbamazepine hydrochloride is described as are two polymorphs of carbamazepine hydrobromide. All are protonated at the amide O atom to give RC(OH)NH2 cations. Prolonged exposure to air results in addition of water to the solid salt forms. Such hydration of carbamazepine hydrobromide simply gives a monohydrated phase, but similar treatment of the equivalent hydrochloride results in partial loss of HCl and the transfer of the remaining proton from the amide group to water to give [carbamazepine][H 3O]0.5[Cl]0.5·H2O. A similar hydronium chloride species is the only product isolated after reaction of the carbamazepine analogue cytenamide with HCl generated in methanol. © 2013 American Chemical Society. Source

Majumder M.,Pharmaterials Ltd. | Majumder M.,University of Reading | Buckton G.,Pharmaterials Ltd. | Buckton G.,University of London | And 5 more authors.
CrystEngComm | Year: 2011

An X-ray amorphous mixture of carbamazepine and indomethacin transforms upon annealing to produce a novel 1:1 cocrystal, whose structure has been determined from laboratory powder X-ray diffraction (PXRD) data. © 2011 The Royal Society of Chemistry. Source

Shankland K.,University of Reading | Markvardsen A.J.,Rutherford Appleton Laboratory | Rowlatt C.,Rutherford Appleton Laboratory | Shankland N.,Crystallografx Ltd. | David W.I.F.,Rutherford Appleton Laboratory
Journal of Applied Crystallography | Year: 2010

Quasi-Newton-Raphson minimization and conjugate gradient minimization have been used to solve the crystal structures of famotidine form B and capsaicin from X-ray powder diffraction data and characterize the χ2 agreement surfaces. One million quasi-Newton-Raphson minimizations found the famotidine global minimum with a frequency of ca 1 in 5000 and the capsaicin global minimum with a frequency of ca 1 in 10 000. These results, which are corroborated by conjugate gradient minimization, demonstrate the existence of numerous pathways from some of the highest points on these χ2 agreement surfaces to the respective global minima, which are passable using only downhill moves. This important observation has significant ramifications for the development of improved structure determination algorithms. © 2010 International Union of Crystallography Printed in Singapore - all rights reserved. Source

Cruickshank L.,University of Strathclyde | Kennedy A.R.,University of Strathclyde | Shankland N.,Crystallografx Ltd.
Journal of Molecular Structure | Year: 2013

Crystallisation of the phenylethylamine neurotransmitter dopamine from basic aqueous solution yielded the 3-phenoxide Zwitterionic tautomer, despite this being a minority form in the solution state. In the crystal structure, dopamine has a dimeric [OCCOH]2 hydrogen bonded catechol motif that expands through NHâ̄O interactions to give a 2-dimensional sheet of classical hydrogen bonds. These sheets are further interconnected by NHâ̄π interactions. The structurally related base tyramine crystallises under similar conditions as a hemihydrate with all four possible species of tyramine present (cationic, anionic, Zwitterionic and neutral) in the crystal structure. Single crystal X-ray diffraction studies at 121 and 293 K showed dynamic hydrogen atom disorder for the phenol/phenoxide group, suggesting that the tyramine speciation observed arises from a solid-state process. © 2013 Elsevier B.V. All rights reserved. Source

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