Abstract The synthesis and full characterization of new chromophores with second order optical nonlinearities containing the 2-phenyl-(5, 6)-nitrobenzimidazole group is reported. Starting from 2-{4-[(4-N, N-dihydroxyethylamino) phenylazo] phenyl}-5 (6)- nitrobenzimidazole, a combined theoretical and experimental approach, including theoretical computations of second order nonlinear optical activity (MNDO/AM1), X-ray ...