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首页> 外文期刊>Chemistry: A European journal >Synthesis, structure, and nonlinear optical properties of cross-conjugated perphenylated iso-polydiacetylenes
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Synthesis, structure, and nonlinear optical properties of cross-conjugated perphenylated iso-polydiacetylenes

机译：交叉共轭全苯基化异聚二乙炔的合成，结构和非线性光学性质

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摘要

Monodisperse, cross-conjugated perphenylated iso-polydiacetylene (iso-PDA) oligomers, ranging from monomer 15 to pentadecamer 25, have been synthesized by using a palladium-catalyzed cross-coupling protocol. Structural characteristics elucidated by X-ray crystallographic analysis demonstrate a non-planar backbone conformation for the oligomers due to the steric interactions between alkylidene phenyl groups. The electronic absorption spectra of the oligomers show a slight red-shift of the maximum absorption wavelength as the chain length increases from dimer 17b to pentadecamer 25, a trend that has saturated by the stage of nonamer 22. Fluorescence spectroscopy confirms that the pendent phenyl groups present on the oligomer framework enhance emission, and the relative emission intensity consistently increases as a function of chain length n. The molecular third-order nonlinearities, gamma, for this oligomer series have been measured via differential optical Kerr effect (DOKE) detection and show a superlinear increase as a function of the oligomer chain length n. Molecular modeling and spectroscopic studies suggest that iso-PDA oligomers (n > 7) adopt a coiled, helical conformation in solution.
机译：已经通过使用钯催化的交叉偶联方案合成了单分散的，交叉共轭的全苯基化的异聚二乙炔（iso-PDA）低聚物，其范围从单体15到十五酮25。通过X射线晶体学分析阐明的结构特征表明，由于亚烷基苯基之间的空间相互作用，该低聚物具有非平面的骨架构象。低聚物的电子吸收光谱显示，随着链长从二聚体17b到十五碳二烯25的增加，最大吸收波长发生轻微的红移，这种趋势已被九聚体22阶段饱和。荧光光谱证实了侧链苯基低聚物骨架上存在的α原子增强了发射，并且相对发射强度作为链长n的函数持续增加。该低聚物系列的分子三阶非线性度γ已通过差分光学克尔效应（DOKE）检测进行了测量，并显示出作为低聚物链长n的函数的超线性增加。分子建模和光谱研究表明，iso-PDA低聚物（n> 7）在溶液中采用螺旋状螺旋构象。

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