Synthesis and properties of weakly coupled dendrimeric multiporphyrin light-harvesting arrays and hole-storage reservoirs
Synthesis and properties of weakly coupled dendrimeric multiporphyrin light-harvesting arrays and hole-storage reservoirs
复制标题
弱耦合树枝状多卟啉光捕获阵列和空穴储存库的合成与性能
DOI：
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发表时间：
2002
期刊：
影响因子：
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通讯作者：
J. Lindsey
中科院分区：
文献类型：
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作者：
M. D. R. Benites;T. E. Johnson;S. Weghorn;Lianhe Yu;P. D. Rao;J. Diers;Sungbong Yang;C. Kirmaier;D. Bocian;D. Holten;J. Lindsey
采用卟啉结构单元的收敛合成提供了含有n个Zn-卟啉（n = 4、8或20）和一个通过二芳基乙炔连接体连接的游离碱-（Fb-）卟啉的树枝状多卟啉阵列。尺寸排阻色谱法广泛用于纯化。该阵列在甲苯或其他溶剂中具有足够的溶解度以用于常规处理。随着尺寸的增加，由于卟啉间激子耦合，强烈的近紫外Soret（S 0 → S2）吸收带变宽、分裂并红移。相比之下，较弱的可见带（S 0 → S1）在从单体一直到21聚体的过程中，其位置或宽度基本保持不变;然而，可见带的分子消光系数与卟啉的数量成比例。类似地，随着阵列变大，卟啉的单电子氧化电位几乎不变。这些结果是指示基态之间的相对较弱的（但显着）的电子耦合之间的相关的最低激发单重态的二芳基乙炔连接的卟啉，因此，保留了个别单位的特征性质的架构增加的复杂性。有效的激发单重态能量转移发生在Zn-卟啉之间，并最终转移到每个阵列中的唯一的Fb-卟啉，其中能量在捕获位点处的总体到达时间随着Zn-卟啉的数目= 1（45 ps）、2（90 ps）、8（105 ps）和20（220 ps）而适度增加。在同一系列中，总能量转换效率分别为98%、96%、96%和92%。研究了21-mer（Zn 20 Fb）的基态空穴存储特性。体电解表明可以从该阵列中去除21个（或更多）电子（例如，每个卟啉上存在一个空穴）以产生稳定的“超荷电”
π-阳离子自由基两者合计，这些结果表明，收敛的积木合成方法提供树枝状多卟啉阵列具有良好的性能，光捕获和空穴存储。
A convergent synthesis employing porphyrin building blocks has afforded dendrimeric multiporphyrin arrays containing n Zn-porphyrins (n = 4, 8, or 20) and one free base- (Fb-) porphyrin joined via diarylethyne linkers. Size exclusion chromatography was used extensively for purification. The arrays have sufficient solubility in toluene or other solvents for routine handling. With increasing size, the intense near-UV Soret (S0 → S2) absorption band broadens, splits, and red shifts due to inter-porphyrin exciton coupling. In contrast, the weaker visible bands (S0 → S1) remain essentially unchanged in position or width in proceeding from the monomer all the way to the 21-mer; however, the molecular extinction coefficients of the visible bands scale with the number of porphyrins. Similarly, the one-electron oxidation potentials of the porphyrins are virtually unchanged as the arrays get larger. These results are indicative of relatively weak (but significant) electronic coupling between ground states and between the photophysically relevant lowest-excited-singlet states of the diarylethyne-linked porphyrins; thus, the characteristic properties of the individual units are retained as the architectures increase in complexity. Efficient excited-singlet-state energy transfer occurs among the Zn-porphyrins and ultimately to the sole Fb-porphyrin in each of the arrays, with the overall arrival time of energy at the trapping site increasing modestly with the number of Zn-porphyrins = 1 (45 ps), 2 (90 ps), 8 (105 ps), and 20 (220 ps). The overall energy-transfer efficiencies are 98%, 96%, 96%, and 92% in the same series. The ground-state hole-storage properties of the 21-mer (Zn20Fb) were examined. Bulk electrolysis indicates that 21 (or more) electrons can be removed from this array (e.g., one hole resides on each porphyrin) to yield a stable “super-charged”
π-cation radical. Taken together, these results indicate that the convergent building-block synthesis approach affords dendrimeric multiporphyrin arrays with favorable properties for light-harvesting and hole storage.
影响因子：
56.9
作者：
LIN, VSY;DIMAGNO, SG;THERIEN, MJ
通讯作者：
THERIEN, MJ