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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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|
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