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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Structural Induced Control of Energy Transfer within Zn(II)-Porphyrin Dendrimers
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Structural Induced Control of Energy Transfer within Zn(II)-Porphyrin Dendrimers

机译：Zn（II）-卟啉树枝状大分子内能量转移的结构诱导控制

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摘要

We report on a study of singlet-singlet annihilation kinetics in a series of Zn(II)-porphyrin-appended dendrimers, where the energy transfer efficiency is significantly improved by extending the molecular chain that connects the light-harvesting chromophores to the dendrimeric backbone with one additional carbon. For the largest dendrimer having 64 Zn(II)-porphyrins, only ~10% of the excitation intensity is needed in order to observe the same extent of annihilation in the dendrimers with the additional carbon in the connecting chain as compared to those without. Complete annihilation, until only one chromophore remains excited, now occurs within subunits of seven chromophores, when half of the chromophores are excited. The improvement of the annihilation efficiency in the largest dendrimer with 64 porphyrins can be explained by the presence of a the two-step delayed annihilation process, involving energy hopping from excited to nonexcited chromophores prior to annihilation. In the smallest dendrimer with only four chromophores, delayed annihilation is not present, since the direct annihilation process is more efficient than the two-step delayed annihilation process. As the dendrimer size increases and the chances of originally exciting two neighboring chromophores decreases, the delayed annihilation process becomes more visible. The additional carbon, added to the connecting chain, results in more favorable chromophore distances and orientations for energy hopping. Hence, the improved energy transfer properties makes the Zn(II)-porphyrin-appended dendrimers with the additional carbon promising candidates as light-harvesting antennas for artificial photosynthesis.
机译：我们报告了一系列附加Zn（II）-卟啉的树枝状大分子的单重态-ni灭动力学的研究，其中通过扩展将集光发色团与树枝状主链连接的分子链来显着提高了能量转移效率一种额外的碳。对于具有64个Zn（II）-卟啉的最大树枝状聚合物，仅需约10％的激发强度，即可观察到树枝状聚合物在连接链中与无碳原子时相比具有相同的an灭程度。完全an没，直到只有一个生色团被激发，现在发生在七个生色团的亚基内，此时一半生色团被激发。具有64个卟啉的最大树枝状大分子的hil灭效率的提高可以通过两步延迟an灭过程的存在来解释，该过程涉及在excited灭之前从激发发色团跃迁到未激发发色团的能量跳跃。在只有四个生色团的最小树枝状聚合物中，不存在延迟an灭，因为直接an灭过程比两步延迟an灭过程更有效。随着树枝状分子尺寸的增加和最初激发两个相邻发色团的机会减少，延迟的an灭过程变得更加明显。添加到连接链上的额外碳会导致更佳的发色团距离和能量跃迁方向。因此，改进的能量转移特性使附有碳（Zn）的卟啉与附加的碳有希望的候选物成为人工光合作用的光收集天线。

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