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Studies in crystal engineering: Steering ability of fluorine in styrylcoumarins

Vishnumunhy, Kodumuru and Row, Tayur Guru N and Venkatesan, Kailasam (1999) Studies in crystal engineering: Steering ability of fluorine in styrylcoumarins. In: Tetrahedron, 55 (13). pp. 4095-4108.

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Official URL: http://dx.doi.org/10.1016/S0040-4020(99)00103-9

Abstract

In continuation of our studies on crystal engineering using fluorine as a steering group, the photobehaviour of di and tri fluoro 4-styrylcoumarins has been examined. It is found that out of the five derivatives, four crystallize into P-packing mode producing syn-HH photodimer upon irradiation whereas the parent hydrocarbon produces an anti K-T dimer. The packing features of the photolabile crystals of 4-(4-fluorostyryl)-6-fluorocoumarin (1), 4-(2,6-difluorostyryl) 6-fluorocoumarin (2) and the photodimer (3a) of 4-(2,6-fluorostyryl)-7-fluorocoumarin (3) have been determined by single crystal X-ray diffraction studies. The stereochemistry of the photodimer of 4-(2-fluorostyryl)-6-fluorocoumarin (4) is deduced based on preliminary X-ray crystallographic data. However, 4-(2,6-difluorostyryl) coumarin (5) is photoinert. The remarkable steering ability of fluorine is established with the molecular packing in the crystal lattice leading to the formation of syn H-H dimer in the above four examples. (C) 1999 Elsevier Science Ltd. All rights reserved.

Item Type: Journal Article
Additional Information: Copyright of this article belongs to Elsevier Science.
Department/Centre: Division of Chemical Sciences > Organic Chemistry
Division of Chemical Sciences > Solid State & Structural Chemistry Unit
Date Deposited: 30 Jun 2011 07:20
Last Modified: 30 Jun 2011 07:20
URI: http://eprints.iisc.ernet.in/id/eprint/38806

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