C60–zinc porphyrin (ZnP) dyad (ZnP–C60) and triad (ZnP–C60–ZnP) were synthesized to probe energy-transfer and electron-transfer processes in the absence and presence of pyridine and diazabicyclooctane (DABCO). The syntheses of C60–ZnP and ZnP–C60–ZnP were carried out by Diels–Alder cycloaddition between sulfolene moiety-containing porphyrin and C60. The photoinduced electron-transfer processes between the spatially positioned C60 and ZnP in the dyad and triad systems were investigated by time-resolved transient absorption and fluorescence measurements with changing solvent polarity. Upon excitation of the ZnP moiety, charge separation via an excited singlet state of ZnP takes place competitively with energy transfer to C60 generating the excited singlet state of C60, from which charge-separated states (ZnP˙+–C60˙− and ZnP˙+–C60˙−–ZnP) are also generated in polar solvents. Rates and efficiencies of energy transfer and charge separation for the triad are higher than those of the dyad. The generated charge-separated species recombine with lifetimes in the rage of 240–330 ns in polar solvents such as DMF, PhCN, and THF for both dyad and triad. In o-dichlorobenzene, although the lifetimes of charge-separated states are very short (<20 ns), coordination of DABCO and pyridine to ZnP in the dyad and triad producing relatively stable coordinated complexes gives rise to prolongation of the charge-separated states up to 460 ns.
研究人员合成了 C60-
锌卟啉(ZnP)二元化合物(ZnP-C60)和三元化合物(ZnP-C60-ZnP),以探测
吡啶和二
氮杂双
环辛烷(
DABCO)不存在和存在时的能量转移和电子转移过程。C60-ZnP 和 ZnP-C60-ZnP 是通过含
亚砜基
卟啉和 C60 之间的 Diels-Alder 环加成反应合成的。在改变溶剂极性的情况下,通过时间分辨瞬态吸收和荧光测量,研究了二元和三元体系中空间位置上的 C60 和 ZnP 之间的光诱导电子转移过程。在极性溶剂中,电荷分离态(ZnP˙+-C60˙- 和 ZnP˙+-C60˙--ZnP)也会由此产生。三元组能量转移和电荷分离的速率和效率均高于二元组。在极性溶剂(如
DMF、PhCN 和 THF)中,生成的电荷分离物种以 240-330 ns 的生命周期重新结合,二元和三元都是如此。在
邻二氯苯中,虽然电荷分离态的寿命很短(<20 ns),但二元和三元中的
DABCO 和
吡啶与 ZnP 配位产生相对稳定的配位络合物,使电荷分离态的寿命延长至 460 ns。