Molecular Design of Synthetic Polypeptides for Nonlinear Optics

Second order molecular susceptibilities β of poly(γ – benzyl L–glutamate)(PBLG) and poly(γ – p–nitrobenzyl L–glutamate) (PNBLG) were determined by means of dc-induced second harmonic generation (dc-SHG technique in solutions at a wavelength of 1064nm as 1.5×10–−29 esu and −4.9×10−29 esu, respectively. Among PBLG, PNBLG and nitrobenzene, it was found that only PNBLG has negative value of β. It follows that the effect of nitrophenyl groups in side chains is dominant for β whereas the contribution of carbonyl groups in main chain is dominant for the permanent dipole moment μ in PNBLG.