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Diffuse scattering study of aspirin forms (I) and (II).

Chan, Eric; Welberry, Thomas; Heerdegen, Aidan; Goossens, Darren

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Full three-dimensional diffuse scattering data have been recorded for both polymorphic forms [(I) and (II)] of aspirin and these data have been analysed using Monte Carlo computer modelling. The observed scattering in form (I) is well reproduced by a simple harmonic model of thermally induced displacements. The data for form (II) show, in addition to thermal diffuse scattering (TDS) similar to that in form (I), diffuse streaks originating from stacking fault-like defects as well as other...[Show more]

dc.contributor.authorChan, Eric
dc.contributor.authorWelberry, Thomas
dc.contributor.authorHeerdegen, Aidan
dc.contributor.authorGoossens, Darren
dc.date.accessioned2015-12-10T22:58:27Z
dc.identifier.issn0108-7681
dc.identifier.urihttp://hdl.handle.net/1885/60862
dc.description.abstractFull three-dimensional diffuse scattering data have been recorded for both polymorphic forms [(I) and (II)] of aspirin and these data have been analysed using Monte Carlo computer modelling. The observed scattering in form (I) is well reproduced by a simple harmonic model of thermally induced displacements. The data for form (II) show, in addition to thermal diffuse scattering (TDS) similar to that in form (I), diffuse streaks originating from stacking fault-like defects as well as other effects that can be attributed to strain induced by these defects. The present study has provided strong evidence that the aspirin form (II) structure is a true polymorph with a structure quite distinct from that of form (I). The diffuse scattering evidence presented shows that crystals of form (II) are essentially composed of large single domains of the form (II) lattice with a relatively small volume fraction of intrinsic planar defects or faults comprising misoriented bilayers of molecular dimers. There is evidence of some local aggregation of these defect bilayers to form small included regions of the form (I) structure. Evidence is also presented that shows that the strain effects arise from the mismatch of molecular packing between the defect region and the surrounding form (II) lattice. This occurs at the edges of the planar defects in the direction only.
dc.publisherMunksgaard International Publishers
dc.sourceActa Crystallographica Section B: Structural Science
dc.subjectKeywords: aspirin; Bi-layer; Computer modelling; Diffuse scattering; Harmonic model; Molecular dimers; Molecular packings; MONTE CARLO; Planar defect; Polymorphic forms; Single domains; Strain effect; Thermally induced; Crystal defects; Harmonic analysis; Oligomers aspirin; diffuse scattering; harmonic model; polymorphism
dc.titleDiffuse scattering study of aspirin forms (I) and (II).
dc.typeJournal article
local.description.notesImported from ARIES
local.identifier.citationvolume66
dc.date.issued2010
local.identifier.absfor030606 - Structural Chemistry and Spectroscopy
local.identifier.absfor091205 - Functional Materials
local.identifier.ariespublicationU4217927xPUB569
local.type.statusPublished Version
local.contributor.affiliationChan, Eric, College of Physical and Mathematical Sciences, ANU
local.contributor.affiliationWelberry, Thomas, College of Physical and Mathematical Sciences, ANU
local.contributor.affiliationHeerdegen, Aidan, College of Physical and Mathematical Sciences, ANU
local.contributor.affiliationGoossens, Darren, College of Physical and Mathematical Sciences, ANU
local.description.embargo2037-12-31
local.bibliographicCitation.issue6
local.bibliographicCitation.startpage696
local.bibliographicCitation.lastpage707
local.identifier.doi10.1107/S0108768110037055
local.identifier.absseo970103 - Expanding Knowledge in the Chemical Sciences
local.identifier.absseo861002 - Ceramics
local.identifier.absseo869804 - Management of Solid Waste from Manufacturing Activities
dc.date.updated2016-02-24T10:44:16Z
local.identifier.scopusID2-s2.0-78649546628
local.identifier.thomsonID000284549900012
CollectionsANU Research Publications

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