EFFECT OF HYDROGEN-BOND ON 2ND-ORDER NONLINEAR-OPTICAL PROPERTY OF 2-ALKYLCARBOXAMIDO-4'-METHOXY-4-NITROTOLAN DERIVATIVES

We have synthesized a series of 2-alkylcarboxamido-4'-methoxy-4-nitrot olan derivatives and studied the second-order nonlinear optical proper ties using the total reflection technique. We measured the infrared ab sorption spectra of the derivatives and examined the absorption peak o f the N-H stretching vibration around 3300 cm(-1), which is sensitive to hydrogen bonding. We observed that the peak frequencies of the nonl inear optical active materials were lower than those of the inactive o nes, and thus found that for 2-alkylcarboxamido-4'-methoxy-4-nitrotola n derivatives the hydrogen bond plays an important role in activating the second-order optical nonlinearity of the material.