Photochromic reactions of two azobenzene chromophores in a chiral cyclohexane moiety

Article abstract of DOI:10.1246/bcsj.72.1623

A chiral cyclohexane containing two photochromic azobenzene units, (1R,2R)-N, N'-bis[4-(phenylazo)benzylidene]- 1,2-cyclohexanediamine, was synthesized in an attempt to construct a molecule which shows a large optical rotation change due to photoirradiation. The CD spectrum dramatically changed depending on the configuration of the two azobenzene units. The specific rotations of (E,E)-, (E,Z)- and (Z,Z)-isomers were - 1400°, -940°, and - 670°, respectively, while that of the monosubstituted chiral cyclohexane, (1R, 2R)-N-[(4-phenylazo)benzylidene]-N'-benzylidene-1,2-cyclohexanediamine ((E)-isomer), was only -470°. There was no difference in the photoisomerization rates of the azobenzen chromophores attached to chiral and nonchiral cyclohexanes.