Department of Chemistry, Indian Institute of Technology Madras, Chennai, 600036, India.
Org Biomol Chem. 2010 May 7;8(9):2260-6. doi: 10.1039/b923441a. Epub 2010 Mar 18.
A diacetylenic molecular hinge bearing two ethynyltriphenylene units (1) has been synthesized. Evidence from (1)H 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 pi-pi interacting closed conformer in solution (equilibrium constant K = 6.5 at 298 K in CDCl(3)) arising from the rotation of the diacetylenic hinge. Unusual fluorescence emission observed from 1 has been assigned to excimer formation arising from intramolecularly pi-pi 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.
已合成出一种带有两个乙炔基三苯乙烯单元的二炔分子铰链（1）。通过与仅带有一个三苯乙烯单元的模型化合物的 1H NMR 和变温 NMR（VT-NMR）比较，证明在溶液中存在开构象和分子内π-π相互作用的闭构象之间的平衡（在 CDCl3 中 298 K 时的平衡常数 K = 6.5），这是由于二炔铰链的旋转引起的。从 1 中观察到的不寻常的荧光发射被分配给来自激发态中分子内 π-π 相互作用的三苯乙烯单元的激基缔合物形成。1 的稳态和皮秒时间分辨荧光光谱几乎相同，对应于分子内激基缔合物发射。
