NASA Glenn Research Center, Polymeric Materials Branch, Cleveland, Ohio 44135, United States.
J Phys Chem A. 2011 May 5;115(17):4157-68. doi: 10.1021/jp111174p. Epub 2011 Apr 7.
Isomeric tetraphenylbenzodifuran systems, benzo[1,2-b:5,4]difuran and benzo[1,2-b:4,5]difuran, containing electron acceptor groups (CF(3), CN, and NO(2)) have been synthesized and studied. Their electronic absorption, fluorescence, two-photon absorption cross sections, and electrochemical properties were investigated. The absorption and emission maxima are red-shifted for the linear-conjugated systems in comparison with the corresponding isomer. Dual fluorescence was observed and the existence of a twisted intramolecular charge transfer state was confirmed by low-temperature emission experiments. Wide HOMO-LUMO energy gaps were obtained ranging from 2.53 to 3.28 eV. HOMO levels were found in the energy range of -6.03 to -6.63 eV while LUMO are within -2.55 to -3.52 eV.
含电子受体基团（CF3、CN 和 NO2）的同分异构四苯并苯并二呋喃体系，苯并[1,2-b:5,4]二呋喃和苯并[1,2-b:4,5]二呋喃，已被合成并进行了研究。研究了它们的电子吸收、荧光、双光子吸收截面和电化学性质。与相应的异构体相比，线性共轭体系的吸收和发射最大值发生红移。通过低温发射实验证实了扭曲的分子内电荷转移态的存在，并观察到了双荧光。获得了从 2.53 到 3.28 eV 的宽 HOMO-LUMO 能隙。HOMO 能级位于-6.03 到-6.63 eV 的能量范围内，而 LUMO 位于-2.55 到-3.52 eV 的范围内。
