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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Electron Transfer in the Supramolecular Donor-Acceptor Dyad of Zinc Hemiporphycene
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Electron Transfer in the Supramolecular Donor-Acceptor Dyad of Zinc Hemiporphycene

机译：锌半卟啉超分子供体-受体二元体中的电子转移

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摘要

In the present study, photoinduced electron transfer (ET) processes of supramolecular donor-acceptor dyads of Zn 2,3,7,8,11,12,17,18-octaethylhemiporphycene (ZnHPc) and axial ligands were investigated by using various spectroscopic methods. The formation of 1:1 dyads was confirmed by absorption spectral change during titration of axial ligand. The association constants were determined from the spectral change. Quenching of the fluorescence intensity was observed when electron acceptor ability of the axial ligand increased. The driving forces for ET were estimated based on the estimated redox potentials and structural parameters. It became clear that various ZnHPc dyads showed ET because of slightly higher donor-ability and larger excitation energy of ZnHPc when compared to the corresponding dyads of Zn porphycene (ZnPcn). The transient absorption spectra during the sub-picosecond laser flash photolysis showed the formation of charge separated state, that is, radical cation of ZnHPc and radical anion of axial ligand, from the singlet excited ZnHPc. The observed ET rates were compared with the previously reported values for Zn porphyrins and ZnPcn. The ET rates of ZnHPc were located between those observed with porphyrins and ZnPcn supramolecular dyads, even when the -ΔG values were similar to each other. This observation was explained on the basis of the variation in reorganization energy and electronic coupling (V) values. Furthermore, distribution of HOMO electron density gave a plausible explanation for the variation in V values of these dyads.
机译：在本研究中，使用各种光谱方法研究了Zn 2,3,7,8,11,12,17,18-八乙基半卟啉（ZnHPc）和轴向配体的超分子供体-受体二元组的光诱导电子转移（ET）过程。 。通过轴向配体滴定过程中的吸收光谱变化确认了1：1二元组的形成。由光谱变化确定缔合常数。当轴向配体的电子受体能力增加时，观察到荧光强度的猝灭。根据估计的氧化还原电势和结构参数，估计了ET的驱动力。很明显，与相应的锌卟啉二元组相比，各种ZnHPc二元组显示出ET的原因是其较高的供体能力和更大的激发能。亚皮秒激光闪光光解过程中的瞬态吸收光谱表明，由单重激发的ZnHPc形成了电荷分离状态，即ZnHPc的自由基阳离子和轴向配体的自由基阴离子。将观察到的ET速率与先前报道的Zn卟啉和ZnPcn值进行比较。 ZnHPc的ET率位于用卟啉和ZnPcn超分子二倍体观察到的ET率之间，即使-ΔG值彼此相似。基于重组能量和电子耦合（V）值的变化来解释此观察结果。此外，HOMO电子密度的分布为这些二元组的V值变化提供了合理的解释。

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