FROM INTERCALATION TO AGGREGATION - NONLINEAR-OPTICAL PROPERTIES OF STILBAZOLIUM CHROMOPHORES-MPS(3) LAYERED HYBRID MATERIALS

A number of cationic chromophores derived from the stilbazolium skelet on have been synthesized and inserted into the transparent layered MPS (3) compounds (M = Mn, Cd, Zn). The NLO properties of the intercalates have been studied. Some of the materials are found to be active for s econd harmonic generation. UV-visible spectroscopy shows that some of the chromophores, once inserted, undergo strong intermolecular interac tions and form J-type aggregates along the inorganic galleries, wherea s others do not. Moreover, we have found that only those intercalates which contain aggregates are NLO active. The results allow us to under stand, at least partially, why the centrosymmetrical MPS(3) host latti ce can yield noncentrosymmetrical intercalates. The host lattice appea rs not so much to impose specific orientations upon the guest species as to favor chromophore aggregation.