New nonlinear optic materials through inclusion chemistry

Nonlinear optic materials are receiving increasing attention from chemists because new materials with as yet unrealized properties are needed for applications in signal processing, image manipulation and optical computing. Molecular aggregation and alignment processes can enhance nonlinear optic properties. Inorganic inclusion hosts provide a multifaceted means of causing these processes to occur in solid materials but inclusion chemistry has remained almost unexplored as a source for new nonlinear optic materials. This work represents the first efforts to produce nonlinear optic materials through aggregation and alignment of included organic guests within inorganic hosts. Several new inclusion materials have been synthesized and characterized. Simple molecular organic guests with large dipole moments generate significant intensities of second harmonic light (SHG) when included within aluminophosphate and related molecular sieve hosts. The SHG intensity can be controlled by variations in guest concentration and structure and host framework charge and structure. The effect is ascribed to molecular aggregation and alignment within the host channels. Layered inorganic materials have been explored for their potential in thin film waveguide structures and as SHG materials. The layered silicic acids show SHG when ion exchanged with large dipole cations. Construction and alignment of methylacetylene polymer chains in acid zeolites has been investigated. Exposure of acid zeolites to the monomer in the vapor phase produces deeply colored materials with spectroscopic properties resembling the pure polymer. Studies of organometallic routes to included semiconductor clusters will also be presented. This work demonstrates that inclusion chemistry using inorganic hosts is a versatile and promising route to new nonlinear optic materials.