Khoj, Manal A., Hughes, Colan Evan, Harris, Kenneth David Maclean ORCID: https://orcid.org/0000-0001-7855-8598 and Kariuki, Benson ORCID: https://orcid.org/0000-0002-8658-3897 2013. Polymorphism in a trans-cinnamic acid derivative exhibiting two distinct β‑type phases: structural properties, [2 + 2] photodimerization reactions, and polymorphic phase transition behavior. Crystal Growth and Design 13 (9) , pp. 4110-4117. 10.1021/cg4009202 |
Abstract
We report the discovery of a rare case of polymorphism among trans-cinnamic acid derivatives in which both polymorphs are classified as β-type structures based on their solidstate structural properties and their solid-state photoreactivity. Specifically, for 3-fluoro-transcinnamic acid, crystallization from many solvent systems leads to formation of one polymorph (denoted β1), although, in a few cases, concomitant crystallization of another polymorph (denoted β2) is also observed. On heating the β1 polymorph, a solid-state phase transition occurs at ca. 119 °C to produce the β2 polymorph. This polymorphic phase transition is irreversible, and the β2 polymorph remains stable on subsequent cooling to ambient temperature. Both the β1 and the β2 polymorphs undergo a topochemical [2 + 2] photodimerization reaction upon UV irradiation to produce 3,3′- difluoro-β-truxinic acid as the photoproduct in almost 100% yield. However, these reactions are associated with complete loss of crystallinity, preventing the structural properties of the directly produced solid photoproduct from being determined by singlecrystal or powder X-ray diffraction techniques.
Item Type: | Article |
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Date Type: | Publication |
Status: | Published |
Schools: | Chemistry |
Subjects: | Q Science > QD Chemistry |
Publisher: | American Chemical Society |
ISSN: | 1528-7483 |
Last Modified: | 24 Oct 2022 12:07 |
URI: | https://orca.cardiff.ac.uk/id/eprint/50578 |
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