The synthesis of aminoazobenzenes and the effect of intermolecular hydrogen bonding on their photoisomerization

Two series of azobenzene derivatives were synthesized so as to investigate the effects of intermolecular hydrogen bonding on their photochemistry. Photoisomerization in polymer matrices was investigated under various irradiation conditions using UV pulsed laser light. Rate constants were calculated according to equations for reversible photoisomerization. Although aminoazobenzenes exhibited faster photoisomerization and larger integral rate constants than the corresponding acetylamino derivatives, the latter compounds displayed faster conversion from the trans to the cis form owing to potential intermolecular hydrogen bonding interaction between the acetylamino groups. Long alkyl chain azobenzenes possessed faster photoisomerization rates than those with short alkyl chains.