Molecular Crystals and Liquid Crystals, Vol.376, 245-250, 2002
Optical Second Harmonic Generation of zwitter ionic molecules aligned on clays
We have attempted to develop a novel Langmuir-Blodgett (LB) film with a non-centrosymmetric molecular alignment by hybridizing a clay and an organic molecule, a D-pi-A zwitter ionic molecule based on amine and TCNQ derivatives. Hybridization is made by forming a monolayer of the organic molecule onto a subphase of an aqueous dispersion of a clay. Second Harmonic Generation (SHG) measurements have revealed that the hybridized LB film possesses non-centrosymmetry in spite of the fact that the used organic molecule has neither a positive charge nor a long alkyl chain. Observations with a Brewster Angle Microscope (BAM) have revealed a clear difference in film properties when pure water as opposed to and a clay suspension is used as a subphase. These facts suggest that the clay plays an important role in the organization of zwitter ionic molecules in the film.