Rational design, synthesis, and characterization of chromophoric supermolecular self-assembled multilayer thin films having very large optical nonlinearities

A method for preparing organized, highly aligned, multifunctional donor-acceptor covalently bonded self-assemblies on silica surfaces is described. Using the organosilane coupling reagent, I₃Si(CH₂)₂C₆H₄CH₂I (Cp), the high-β chromophore, 4-[N,N-bis(3-hydroxypropyl)amino]styryl-4′-pyridine (Ch) can be easily linked to surfaces via quaternization. Additional chromophore layer can be built up in this manner using chlorosilane/polyvinylalcohol as an intervening structural layer. These multilayer structures have been characterized by FTIR-ATR, UV-vis spectroscopy, advancing contact angle, and second harmonic generation measurements. The studies of NLO properties reveal good structural uniformity and second order susceptibilities χ_zzz⁽²⁾ as high as 6 × 10^-7 esu for a single CpCh monolayer and 2 × 10^-7 esu for multilayer superlattices (λ = 1064 nm).