Nitrogen and Oxygen Donors in Nonlinear Optical Materials: Effects of Alkyl vs Phenyl Substitution on the Molecular Hyperpolarizability

This is the authors' abstract. We don't add key points for this paper.

The second-order nonlinear optical response of amine and phenol/ether derivatives ( 1 − 8 ) has been evaluated using experimental and theoretical techniques. Electric-field-induced second-harmonic generation (EFISH) measurements establish that N -phenyl substitution of 4-nitroaniline ( 1 ) produces a greater increase in molecular hyperpolarizability than N -methyl substitution. In contrast, O -phenyl substitution of 4-nitrophenol ( 6 ) produces a smaller increase in hyperpolarizability than O -methyl substitution. Neither the enhancement of hyperpolarizability upon N -phenyl substitution nor the differential substituent effect is anticipated on the basis of qualitative arguments. Careful theoretical analysis using semiempirical sum-over-states and finite field calculations provide explanations for both observed effects.