Scanning second-harmonic microscopy of a thin film of σ-π copolymer with 2,2′-bipyridine in the backbone

Scanning second-harmonic microscopy was used to study the lateral distribution of the second-order optical nonlinearity of a σ-π copolymer [poly(disilanylene-2,2′-bipyridine-5,5′-diyl) ruthenium complex (PDSBpy-Ru)] thin film on a glass substrate. The orientation of the dipolar chromophores and establishment of the noncentrosymmetry required by the macroscopic second-order optical nonlinearity were resulted from natural coordination of the PDSBpy-Ru molecules to the surface Si-O-H groups on the glass substrate. A homogeneous lateral distribution of the coordination-induced poling was observed.