LASER FLASH-PHOTOLYSIS STUDY OF THE PRIMARY PROCESSES IN THE PHOTOCHROMIC REACTION OF 1-ACYLOXY-2-METHOXYANTHRAQUINONES

The nanosecond laser flash photolysis (time resolution 3 ns) has been used to study the primary processes in photochromic reaction of three O-acylic derivatives of 1-oxy-2-methoxyanthraquinone with methyl (I), ethoxyl (II) and diethylamino (III) in migrating acyl. The triplet-tri plet absorption spectra of the reactive triplet states of quinones II and III were detected. The triplet and ground states absorption spectr a of the photoproduct (ana-quinone) were observed; the quantum yields of ana-quinone formation and the rate constants of all elementary step s were measured in toluene at room temperature. It was confirmed in th e present work that photochemical migration of acyl groups is an adiab atic process occurring on the triplet potential energy surface.