Institut für Physik, Photobiophysik, Humboldt-Universität zu Berlin, Newtonstr. 15, D-12489 Berlin, Germany.
Phys Chem Chem Phys. 2013 May 14;15(18):6912-9. doi: 10.1039/c3cp50576f. Epub 2013 Apr 2.
Boron dipyrromethenes (BDPs) are excellent building blocks for design of artificial light harvesting and charge separation systems. In the present work, we report the results of photophysical studies of a novel dyad, in which a BDP and a mono-styryl BDP (MSBDP) are covalently linked to each other at the meso-position via a p-phenylene unit. It was found that the photophysical properties of the dyad dissolved in polar as well as nonpolar solvents are strongly affected by two different types of interactions between the BDP and MSBDP parts, namely excitation energy transfer and photoinduced electron transfer. The first process delivers the excitation energy to the first excited singlet state of the MSBDP-part upon excitation of the BDP unit. The direct or indirect (via excitation energy transfer) population of the first excited singlet state of the MSBDP moiety is followed by hole transfer to generate the charge-separated state. In non-polar toluene, the probability of charge separation is low, whereas in polar acetonitrile the charge separation quantum yield is close to unity, resulting in strong quenching of the MSBDP fluorescence.
硼二吡咯甲烷（BDP）是设计人工光捕获和电荷分离系统的理想构建模块。在本工作中，我们报道了一种新型偶联物的光物理研究结果，其中通过亚苯基单元将 BDP 和单苯乙烯基 BDP（MSBDP）共价键合到彼此的中位。结果发现，偶联物在极性和非极性溶剂中的光物理性质受到 BDP 和 MSBDP 部分之间两种不同类型相互作用的强烈影响，即激发能量转移和光致电子转移。第一个过程在激发 BDP 单元时将激发能量传递到 MSBDP 部分的第一激发单线态。MSBDP 部分的第一激发单线态的直接或间接（通过激发能量转移）填充随后是空穴转移以产生电荷分离状态。在非极性甲苯中，电荷分离的概率较低，而在极性乙腈中，电荷分离量子产率接近 1，导致 MSBDP 荧光强烈猝灭。
