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dc.contributor.authorSrirambhatla, Vijay K.
dc.contributor.authorGuo, Rui
dc.contributor.authorDawson, Daniel M.
dc.contributor.authorPrice, Sarah L.
dc.contributor.authorFlorence, Alastair J.
dc.identifier.citationSrirambhatla , V K , Guo , R , Dawson , D M , Price , S L & Florence , A J 2020 , ' Reversible, two-step single-crystal to single-crystal phase transitions between desloratadine forms I, II, and III ' , Crystal Growth & Design , vol. Articles ASAP .
dc.identifier.otherPURE: 266484900
dc.identifier.otherPURE UUID: 6b85f788-70d7-49cc-b438-992d920a78ec
dc.identifier.otherORCID: /0000-0002-8110-4535/work/69463348
dc.identifier.otherScopus: 85081157132
dc.identifier.otherWOS: 000518701900048
dc.descriptionThis work was supported by EPSRC (EP/K039229/1). ARCHER time was provided via our membership of the UK’s HEC Materials Chemistry Consortium, which is funded by EPSRC (EP/L000202).en
dc.description.abstractSingle-crystal to single-crystal polymorphic transformations in molecular solids are relatively rare, with changes in crystal structure more commonly leading to destruction of the parent crystal. However, the structural basis for such transitions is of considerable interest given the changes in material properties that can result. The antihistamine desloratadine displays a two-step, reversible single-crystal to single-crystal phase transition during heating/cooling cycles between three conformational polymorphs: the low temperature form I, a polytypic intermediate form II, and the high temperature form III. The two-step transition involves a sequential flipping of the piperidine rings of desloratadine molecules in the crystals, which induce reversible micrometer-scale contraction on heating and expansion on cooling of the largest face of a desloratadine single crystal. Distinct, slow-moving phase boundaries, originating on the (001) face of the crystal, were observed sweeping through the entire crystal in hot-stage microscopy, suggesting a single nucleation event. Computational spectroscopy, using periodic DFT-D phonon calculations, reproduces the experimental variable-temperatureTHz-Raman spectra and rules out the possibility of the phase transformations occurring via any classical soft mode. A combination of variable-temperature powder X-ray diffraction, solid-state NMR, and computational spectroscopy provides a detailed molecular description of the phase transitions, indicating a first-order diffusionless process between I → II and II → III, wherein both conformational changes and lattice distortions occur simultaneously in the crystal lattice. The study indicates that a nucleation and growth mechanism is compatible with concerted movements producing a conformational change in organic molecular crystals.
dc.relation.ispartofCrystal Growth & Designen
dc.rightsCopyright © 2020 American Chemical Society. This is an open access article published under a Creative Commons Attribution (CC-BY) License, which permits unrestricted use, distribution and reproduction in any medium, provided the author and source are cited.en
dc.subjectCrystal structureen
dc.subjectPhysical and chemical processesen
dc.subjectPhase transitionsen
dc.subjectQD Chemistryen
dc.titleReversible, two-step single-crystal to single-crystal phase transitions between desloratadine forms I, II, and IIIen
dc.typeJournal articleen
dc.description.versionPublisher PDFen
dc.contributor.institutionUniversity of St Andrews.EaSTCHEMen
dc.contributor.institutionUniversity of St Andrews.School of Chemistryen
dc.description.statusPeer revieweden

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