Bhattacharyya, K. ; Ramamurthy, V. ; Das, P. K. (1987) A laser flash photolysis study of pivalothiophenone triplets: steric and electronic effects in thione photoreaction kinetics The Journal of Physical Chemistry, 91 (22). pp. 5626-5631. ISSN 0022-3654
Full text not available from this repository.
Official URL: http://pubs.acs.org/doi/abs/10.1021/j100306a026
Related URL: http://dx.doi.org/10.1021/j100306a026
Abstract
Upon laser pulse excitation (Aex = 532 nm) into the lowest-lying '(n,a*) band system, pivalothiophenones in benzene solutions give rise to short-lived triplets (Ama: = 325-335 nm, em: = (1 1-15) X lo3 M-' cm-I) with quantitative intersystem crossing efficiencies. The triplet yields decrease slightly (by 10-30%) upon changing A, to 308 nm (Le., upon excitation into S2). Kinetic data are presented for intrinsic triplet lifetimes, self-quenching, and quenching by oxygen, di-tert-butylnitroxy radical, and various reagents capable of interacting with the triplets via energy, electron, or hydrogen-atom transfer and by biradical formation (possibly leading to cycloaddition). The mechanisms of the quenching processes are discussed. Relative to rigid aromatic thiones, namely, xanthione and thiocoumarin, the interaction of pivalothiophenone triplets with most of the quenchers are kinetically inefficient. This is interpreted primarily as a manifestation of the steric crowding at positions a to the thiocarbonyl group.
Item Type: | Article |
---|---|
Source: | Copyright of this article belongs to American Chemical Society. |
ID Code: | 55871 |
Deposited On: | 19 Aug 2011 07:46 |
Last Modified: | 19 Aug 2011 07:46 |
Repository Staff Only: item control page