Department of Chemistry and the Macromolecular Science and Engineering Program, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109-1055, USA.
J Org Chem. 2009 Dec 4;74(23):9112-9. doi: 10.1021/jo902044a.
A series of six-ring oligothiophenes containing one to three degrees of ring fusion were assembled by a combination of metal-catalyzed Stille cross-coupling and oxidative homocoupling reactions. The effect of position and extent of ring fusion on the electronic properties was studied by UV-vis absorption and fluorescence spectroscopies, and these data were interpreted in the context of TD-DFT computational analysis. Within each set of regioisomers, a slight red shift is revealed in the onset of the UV-vis absorption spectra when the fused-ring unit is located nearer to the periphery of the oligomer, indicating a narrower HOMO-LUMO gap. Incorporation of the unit of ring fusion toward the interior of the oligomer results in a decrease in the longest wavelength emission maximum and a reduced Stokes shift, and is accompanied by an increase in fluorescence quantum yield.
一系列含有一至三个环融合度的六元环寡聚噻吩通过金属催化的 Stille 交叉偶联和氧化偶联反应组合而成。通过紫外可见吸收光谱和荧光光谱研究了环融合的位置和程度对电子性质的影响，并在 TD-DFT 计算分析的背景下对这些数据进行了解释。在每组区域异构体中，当融合环单元更靠近寡聚物的外围时，紫外可见吸收光谱的起始处略有红移，表明 HOMO-LUMO 能隙变窄。将融合环单元引入寡聚物内部会导致最长波长发射最大值减小和斯托克斯位移减小，并伴随着荧光量子产率的增加。
