Studies in crystal engineering: Effect of fluorine substitution in crystal packing and topological photodimerization of styryl coumarins in the solid state

Vishnumurthy, Kodumuru and Row, Tayur Guru G and Venkatesan, Kailasam (1996) Studies in crystal engineering: Effect of fluorine substitution in crystal packing and topological photodimerization of styryl coumarins in the solid state. In: Perkin Transactions 2 (7). pp. 1475-1478.

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Abstract

Styryl coumarins generally yield centrosymmetric (alpha-mode, anti-HT) photodimers when subjected to irradiation in the solid state, However, the substitution of fluorine dramatically alters the packing mode and steers the molecules 4-(4-fluorostyryl)coumarin 1 and 4-(2-fluorostyryl)coumarin 2 to form a stereospecific photodimer, beta-mode, syn-HH across the styrenic double bond (yield 78-85%). The stereochemistry of the photodimer 2a has been established by X-ray crystallography. There is no evidence for the presence of C-H ... F interactions. The true nature of the weak atom-atom interactions called into play when fluorine is substituted is not clear, It is observed that the fluoro substituted compounds have greater crystal density than the corresponding unsubstituted ones.

Item Type:	Journal Article
Additional Information:	Copyright of this article belongs to Royal Society of Chemistry.
Department/Centre:	Division of Chemical Sciences > Organic Chemistry Division of Chemical Sciences > Solid State & Structural Chemistry Unit
Date Deposited:	13 May 2011 06:28
Last Modified:	13 May 2011 06:28
URI:	http://eprints.iisc.ernet.in/id/eprint/37594

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