Photoinitiated azo‐hydrazo tautomerizm of 1‐p‐ toluenesulphonylazo‐2,4,6,8‐tetrakis (tert‐butyl)phenoxazine

A novel photochromic compound with NH‐N intramolecular H‐bond (1‐p‐toluenesulphonylazo‐ 2,4,6,8‐tetrakis(tert‐butyl)phenoxazine) and the corresponding model structures (1‐oxo‐2,4,6,8‐tetrakis(tertbutyl) phenoxazine, 2,4,5,7‐tetrakis (tert‐butyl )‐1‐( veratroylazo ) phenoxazine, 2,4,5,7‐tetrakis ( tert‐butyl )‐Nacetyl‐ 1‐(p‐toluenesulphonylazo)phenoxazine) have been synthesized and their spectral and photochemical properties are studied. The photochromic transformations observed are found to be conditioned by ESIPT (as a primary step) followed by E‐Z isomerisation about N–N‐bond.