SOLID-STATE PHOTOCHROMISM OF ANILS

The anils of ortho-hydroxybenzaldehyde comprise a chemical system whic h exhibits the properties of solid state photochromism and thermochrom ism. These properties are exclusive in this system and therefore there is a problem which may be described as the relation between photochro mism and thermochromism on the one hand and crystal structure on the o ther. Thus in this work the topochemical factors responsible for these properties are explored and ''structural engineering'' approach are a pplied in order to prepare solid anils which are photochromic and/or t hermochromic at will. Literature data on crystal structure and photo-b ehaviour of anils are presented and discussed under the same light in order to have a more complete understanding of the problem.