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M. Ya. Mel'nikov, V. I. Pergushov and J. A. Weinstein

Chemistry of the Electroncally Excited Intermediates (Radicals, Radical Ions, the Excited States of Coordination Compounds). The Matrix Effects and Molecular Organization of Processes

Abstract

Reactivity of electronically excited intermediates of different types (radicals, radical-ions, excited states of coordination compounds) is discussed. For different classes of radical anions the main types of photochemical transformations have been identified and characterised quantitatively through establishing kinetic rules governing these transformations. The ways of controlling efficiency and direction of competitive photochemical pathways through changes in the molecular organization of the media and intermediates, and by using various matrix effects have been established. The mechanism of photoradical ageing of various polymer materials has been elucidated. The new type of unbranched chain reactions in solid state - photoradical chain reactions - has been discovered and studied experimentally in detail. The development of such reactions in solid state has been followed in spatial and time domains, which has enabled us to predict the changes in the properties of the materials, including those associated with photoradical ageing. A conceptually new method of investigating of radical reactions - matrix isolation on activated surfaces - has been developed and allowed for obtaining unique information on novel, previously unknown reactions of radical species, and on inversion of selectivity in these processes. A new method of controlling photoreactivity of coordination compounds -structural reorganization in the excited state through formation of a transient three-electron sulphur-sulfur bond - has been designed and tested by a combination of advanced spectroscopic techniques.
Moscow University Chemistry Bulletin.
2005, Vol. 46, No. 3, P. 168
   

Copyright (C) Chemistry Dept., Moscow State University, 2002
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