Crystal chemistry and photomechanical behavior of 3,4-dimethoxycinnamic acid: correlation between maximum yield in the solid-state topochemical reaction and cooperative molecular motion

Mishra, Manish Kumar and Mukherjee, Arijit and Ramamurty, Upadrasta and Desiraju, Gautam R (2015) Crystal chemistry and photomechanical behavior of 3,4-dimethoxycinnamic acid: correlation between maximum yield in the solid-state topochemical reaction and cooperative molecular motion. In: IUCrJ, 2 (6). pp. 653-660.

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Abstract

A new monoclinic polymorph, form II (P2(1)/c, Z = 4), has been isolated for 3,4-dimethoxycinnamic acid (DMCA). Its solid-state 2 + 2 photoreaction to the corresponding alpha-truxillic acid is different from that of the first polymorph, the triclinic form I (P (1) over bar, Z = 4) that was reported in 1984. The crystal structures of the two forms are rather different. The two polymorphs also exhibit different photomechanical properties. Form I exhibits photosalient behavior but this effect is absent in form II. These properties can be explained on the basis of the crystal packing in the two forms. The nanoindentation technique is used to shed further insights into these structure-property relationships. A faster photoreaction in form I and a higher yield in form II are rationalized on the basis of the mechanical properties of the individual crystal forms. It is suggested that both Schmidt-type and Kaupp-type topochemistry are applicable for the solid-state trans-cinnamic acid photodimerization reaction. Form I of DMCA is more plastic and seems to react under Kaupp-type conditions with maximum molecular movements. Form II is more brittle, and its interlocked structure seems to favor Schmidt-type topochemistry with minimum molecular movement.

Item Type:	Journal Article
Publication:	IUCrJ
Publisher:	INT UNION CRYSTALLOGRAPHY
Additional Information:	Copy right for this article belongs to the INT UNION CRYSTALLOGRAPHY, 2 ABBEY SQ, CHESTER, CH1 2HU, ENGLAND
Keywords:	crystal engineering; cinnamic acid; photosalient; nanoindentation; polymorphism
Department/Centre:	Division of Chemical Sciences > Solid State & Structural Chemistry Unit Division of Mechanical Sciences > Materials Engineering (formerly Metallurgy)
Date Deposited:	10 Dec 2015 06:03
Last Modified:	10 Dec 2015 06:03
URI:	http://eprints.iisc.ac.in/id/eprint/52879

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