Thermally activated and light-induced metal ion complexation of 5 '-(hydroxy)spiroindolinonaphthooxazines in polar solvents

摘要

Chelation with Al(III), Fe(II) or Cu(II) of the open photomerocyanine form obtained under steady irradiation of spiroindolinonaphthooxazines, with a hydroxyl group at the 5' position in the naphthooxazine moiety, induces a slight hypsochromic shift of its visible absorption band and increases the lifetime of this form, slowing down its thermal bleaching in the dark (rate constant similar to10(-3) s(-1)). Complexation with Al(III), Fe(II) or Cu(II) allows the spiroindolinonaphthooxazines to isomerize to their open coloured form even under dark conditions giving a complex spectroscopically identical to the photoinduced product. The activation energy of thermal complexation is independent of the metal ion which implies the ring opening as the rate determining step. (C) 2004 Elsevier Ltd. All rights reserved.