Optical information recording medium

Claim 1

An optical information recording medium which comprises a substrate and a recording layer at least 100 Å thick, containing at least one of the compounds represented by the formulas (I) and (II) ##STR28## in which R 1 , R 2 , R 3 and R 4 may be the same or different and each is an alkyl group, an alkenyl group, an alkoxy group or an aralkyl group, these groups being optionally substituted; R 5 is an alkyl group having 1 to 3 carbon atoms which is unsubstituted or substituted; R 6 is an alkyl group having 3 to 18 carbon atoms which is unsubstituted or substituted, --(CH 2 ) a --OCOR or --(CH 2 ) a --OR where R is an alkyl group of 1 to 3 carbon atoms and a is 1 to 5, with the proviso that when R 5 is C3 alkyl, R 6 is not C 3 alkyl; R 7 is hydrogen, an alkyl group, an alkenyl group, an alkoxy group, a hydroxyl group, a halogen atom, an unsubstituted or substituted amino group, an alkanoyloxy group or an aralkyl group; Z represents atom groups necessary to form 4 to 8-membered rings, preferably 5- to 6-membered ring, which are unsubstituted or substituted and may be condensed with an aromatic ring; A is --CH═CH-- 1 or --CH═CH--CH═ 1 ; B is ═CH--CH═ m or --CH═CH-- m CH═; m and 1 is 0 or 1 to 3, and n is 2 or 3; and X is an acid anion, and the benzene nuclei in the indole and indolenine rings may be substituted by one or more groups selected from an alkyl group, an alkenyl group, an alkoxy group, a halogen atom or an aralkyl group, or may be condensed with one or more benzene rings.