Unusual fluorescene emission from ethynyltriphenylene-substituted diacetylenic molecular hinge. Formation of intramolecular excimer
作者:Ritesh Nandy、Sethuraman Sankararaman
DOI:10.1039/b923441a
日期:——
A diacetylenic molecular hinge bearing two ethynyltriphenylene units (1) has been synthesized. Evidence from 1H NMR and variable temperature NMR (VT-NMR) of 1 in comparison to model compounds bearing only one triphenylene unit suggests that there is an equilibrium between the open conformer and the intramolecularly π–π interacting closed conformer in solution (equilibrium constant K = 6.5 at 298 K in CDCl3) arising from the rotation of the diacetylenic hinge. Unusual fluorescence emission observed from 1 has been assigned to excimer formation arising from intramolecularly π–π interacting triphenylene units in the excited state. Steady state and picosecond time resolved fluorescence spectra of 1 were nearly identical and corresponded to intramolecular excimer emission.
合成了带有两个乙炔基苯并菲单元 (1) 的二乙炔分子铰链。 1 的 1 H NMR 和变温 NMR (VT-NMR) 与仅含有一个苯并菲单元的模型化合物相比的证据表明,溶液中开放构象异构体和分子内 π-π 相互作用的闭合构象异构体之间存在平衡(平衡常数 K = 6.5 at 298 K in CDCl3) 由二乙炔铰链的旋转产生。从 1 观察到的异常荧光发射被归因于激发态下分子内 π-π 相互作用的苯并菲单元形成准分子。 1 的稳态和皮秒时间分辨荧光光谱几乎相同并且对应于分子内准分子发射。