Schiff base quinone complexes and optical recording materials comprising the same

A method for preventing fading comprising adding a compound of formula (1b):

• ##STR61## to a member selected from the group consisting of heat developable photosensitive materials, silver halide photosensitive materials, silver halide photosensitive materials, optical recording materials, medical diagnostic materials, ink and paint;
• wherein, R.sup.3, R.sup.4, R.sup.5, and R.sup.6 are independently selected from the group consisting of hydrogen, halogen, alkyl, alkenyl, alkynyl, alkoxy, alkylcarbonyl, carbamoyl, acylamino, alkoxycarbonyl group, and a group of non-metallic atoms necessary to form a hydrocarbon or aromatic ring, rings A and B may be connected directly or through a non-metallic atom, letter n is an integer of 1 to 4, and M.sup.2 is a metal atom selected from the group consisting of Ca, Ba, Y, La, Nd, Sm, Gd, Tb, Dy and Yb.

A method for dyeing comprising adding a compound of formula (1b):

• ##STR62## to a member of the group consisting of photographic antihalation materials, medical diagnostic materials, filters, ink and paint;
• wherein R.sup.3, R.sup.4, R.sup.5, and R.sup.6 are independently selected from the group consisting of hydrogen, halogen, alkyl, alkenyl, alkynyl, alkoxy, alkycarbonyl carbamoyl, acylamino, alkoxycarbonyl group, and a group of non-metallic atoms necessary to form a hydrocarbon or aromatic ring, rings A and B may be connected directly or through a non-metallic atom, letter n is an integer of 1 to 4, and M.sup.2 is a metal atom.