Short-lived triplets of aliphatic thioketenes

Bhattacharyya, K and Ramamurthy, V and Das, PK and Sharat, S (1986) Short-lived triplets of aliphatic thioketenes. In: Journal of Photochemistry, 35 (3). pp. 299-309.

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Abstract

The photophysical behavior of the triplets of three aliphatic thioketenes, namely di-tert-butylthioketene (1), 2,6-di-tert-butylcyclohexylthioketene (2) and 2,2,6,6-tetramethylcyclohexylthioketene, has been studied in fluid solutions at room temperature by nanosecond laser flash photolysis. Upon 532 nm laser excitation into the S1 state, the thioketenes in concentrated benzene solutions produce very short-lived transient absorptions (τ < 5 ns; λmax ≈ 450 nm) attributable to their triplets. The photogeneration of the latter under S1 excitation has also been established by energy transfer to all-trans-1,6-diphenyl-1,3,5-hexatriene. The factors which render the triplet lifetimes short are shown to be intrinsic in origin (rather than self-quenching). Unlike thiocarbonyl compounds in general, the thioketenes posses low intersystem crossing yields (less than 0.1 in benzene). From the kinetics of the quenching of a series of sensitizer triplets by 1 and 2, the thioketene triplet energies are estimated to be 43 – 44 kcal mol−1.

Item Type:	Journal Article
Publication:	Journal of Photochemistry
Publisher:	Elsevier Science
Additional Information:	Copyright of this article belongs to Elsevier Science.
Department/Centre:	Division of Chemical Sciences > Organic Chemistry
Date Deposited:	07 Feb 2010 10:30
Last Modified:	19 Sep 2010 05:32
URI:	http://eprints.iisc.ac.in/id/eprint/20347

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