Photochromic processes in di(mercaptoquinolinato)Ni(II) complex and perfluordiphenyl disulfide solutions

Abstract

Laser flash photolysis was used to study the nature and reactions of intermediates for a novel photochromic system consisting of perfluorodiphenyl disulfide (F(5)C(6)SSC(6)F(5) = (SBF)(2)) and a flat di(mercaptoquinolinato)Ni(II) (Ni(SC(6)H(3)NC(3)H(3))(2) = Ni(SR)(2)) complex in benzene solutions. Under UV-radiation disulfide dissociates into two sulfur-containing radicals (F(5)C(6)S˙ = ˙SBF) that vanish in recombination. In the presence of the Ni(SR)(2) complex recombination competes with radical coordination yielding the radical (SBF˙)Ni(SR)(2) complex. This complex has an absorption band in the visible region and disappears in the second-order reaction when radical-complex recombines into dimer ((RS)(2)Ni(SBF)(2)Ni(SR)(2)). Subsequent dimer dissociation into initial disulfide and two Ni(SR)(2) complexes completes the photochromic cycle.