Crystal structures, two-photon absorption and theoretical calculation of a series of bis-vinylpyridine compounds synthesized by one-step solid state reaction

Three bis-vinylpyridine compounds (4,4′-bis(2-vinylpyridine)biphenyl L1, 4,4′-bis(3-vinylpyridine) biphenyl L2, and 4,4′-bis (4-vinylpyridine)biphenyl L3) were synthesized by one-step solid-state reactions at room temperature, giving nearly quantitative yields. The compounds obtained were fully characterized by IR, MS and NMR spectroscopies. The structures of L2 and L3 were determined by single crystal X-ray diffraction analysis. No noticeable solvatochromism was observed in either one-photon absorption or one-photon excited fluorescence spectra. All of the compounds have high fluorescence quantum yields and long fluorescence lifetime. The linear and nonlinear optical properties of the compounds were investigated both experimentally and theoretically. Interestingly, the position of the nitrogen atom from pyridine influences their two-photon absorption across-sections.