Enhancement of the molecular hyperpolarizability by a supramolecular amylose–dye inclusion complex, studied by hyper-Rayleigh scattering with fluorescence suppression

The first hyperpolarizability β of a free hemicyanine dye and a homologue dye included in a supramolecular complex have been determined by hyper-Rayleigh scattering. Since the inclusion complex is fluorescent, high-frequency demodulation of the time-delayed multiphoton fluorescence has been used to retrieve a fluorescence-free inherent value for its first hyperpolarizability. The free dye does not exhibit fluorescence; the inclusion induces fluorescence with a lifetime of 4.8±0.1 ns; and the inclusion complex has a fluorescence-free value for its dispersion-free first hyperpolarizability β0 of approximately twice that for the free dye ((200±5)×10−30 vs. (100±10)×10−30 esu)). The enhanced polar orientation of this complex in thin films, and better thermal and mechanical stability, together with this increase in molecular nonlinearity confirm inclusion as a way to engineer efficient macroscopic arrangements for nonlinear optics.