SUBSTITUENT EFFECTS ON ABSORPTION MAXIMA OF N-(4-SUBSTITUTED PHENYL)PYRROLE, 4-DIAZOLE, 4-TRIAZOLE DERIVATIVES AND THEIR 2ND-ORDER NONLINEAR-OPTICAL PROPERTIES

N-(4-Substituted phenyl) azoles possessing electron attracting substituents were studied from the viewpoints of substitutent effect on absorption maxima (lambda(max)) and nonlinear optical properties. The substitution effect on lambda(max) was studied from the viewpoint of contribution ratio of resonance effect and inductive effect. A substitutent constant, which has much more resonance contribution than sigma(P) or sigma(P)-, is necessary to describe good relationship. The substituent constant is symbolized by <sigma> in this paper, which has shown good correlation with 1/lambda(max) in negative mode. On the other hand, molecular hyperpolarizabilities(beta) have shown good correlation with sigma(P)-. From the viewpoint of nonlinear optical material, 1-(4-acetylphenyl)-1H-1,2,4-triazole (13), which is superior in blue-light transparency to nitro derivatives, were found as expected one. From oriented gas model using crystal structure and beta(ij) values calculated, nonlinear optical constants (d(ij)'s) of 13 are obtained to be 16.2 pm/V (d22) and 21.5 pm/V (d23).