| abstract |
Carbonyloxy-substituted azulenesquaric acid dyes of the formula <IMAGE> where L is C1-C12-alkylene which may be substituted by phenyl, R1 is C1-C12-alkyl, monounsaturated or polyunsaturated C3-C12-alkenyl, which may be phenyl-substituted, C3-C7-cycloalkyl, C3-C7-cycloalkenyl, substituted or unsubstituted phenyl, pyrrolyl, furanyl, thienyl or pyridyl and R2, R3, R4 and R5 are each independently of the others hydrogen or substituted or unsubstituted C1-C12-alkyl, with the proviso that when R3 is hydrogen the positions of the substituents CH2-L-O-CO-R1 and R4 on either or both azulene rings may also be interchanged with each other within an azulene ring, are useful in an optical recording medium. |