Molecular Origins of the Nonlinear Optical Responses of a Series of α-(X-2-Pyridylamino)-o-cresol Chromophores from Concerted X-ray Diffraction, Hyper-Rayleigh Scattering, and Ab Initio Calculations

Abstract

Faster transmission rates are desperately needed in the telecommunications industry, given that global demand for signal transmission already outstrips supply. New organic nonlinear optical (NLO) materials offer a prospective solution for the telecommunications industry given that they exhibit shorter optical response times compared to their inorganic counterparts. α-(X-2-Pyridylamino)-o-cresol-type motifs with their donor−π–acceptor (D−π–A) architecture and high level of π-conjugation are expected to afford high levels of intramolecular charge transfer (ICT). Such ICT phenomena will contribute to these types of molecules having faster optical response times and large (hyper)polarizabilities. The linear and second-order NLO properties of three new α-(X-2-pyridylamino)-o-cresol motifs (X = 4-CH3 (1); 5-Cl (2); 3,5-Cl (3)) were hence evaluated. NLO structure–function relationships were established in terms of their ICT characteristics and molecular hyperpolarizabilities (β). Given the typically large errors...