Acid-triggering of light-induced charge-separation in hybrid organic/inorganic molecular photoactive dyads for harnessing solar energy
Acid-triggering of light-induced charge-separation in hybrid organic/inorganic molecular photoactive dyads for harnessing solar energy
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DOI：
10.1039/d0qi01368d
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发表时间：
2021-03-21
影响因子：
7
通讯作者：
Gibson, Elizabeth A.
中科院分区：
文献类型：
--
作者：
Benazzi, Elisabetta;Karlsson, Joshua;Gibson, Elizabeth A.
描述了光激发共价多金属氧酸盐-bodipy 缀合物中 H+ 调制的电荷转移。杂化有机/无机分子光活性二元体基于通过有机锡连接体共价接枝到 bodipy (BOD) 光敏剂的 Keggin 型多金属氧酸盐（POM，其中 K-M = [PM11O39] 且 M = Mo 或 W）。光敏剂和 POM 的相对电势一致，使得光诱导电子从 BOD 转移到 POM 对于多钼酸盐 K-Sn(Mo)[BOD] 是允许的，但对于多氧钨酸盐类似物 K-Sn(W)[BOD] 则无效。在这两种情况下，酸的添加仅改变 POM 的氧化还原电位，以增加电子转移的驱动力。这导致 K-Sn(W)[BOD] 在酸存在下发生电荷分离。向 K-Sn(Mo)[BOD] 中添加酸可将电荷分离加速一个数量级（从 2 ns 到 200 ps），并伴随着电荷复合的减速，导致电荷分离状态寿命高达 1.3 μs。这种行为与质子耦合电子转移一致，此前已通过 POM 的电化学观察到了这一现象，但这项研究首次表明质子化对光诱导电子转移的影响。
H+ modulated charge-transfer in photoexcited covalent polyoxometalate-bodipy conjugates is described. The hybrid organic/inorganic molecular photoactive dyads are based on Keggin-type polyoxometalates (POMs, where K-M = [PM11O39] and M = Mo or W) covalently grafted via an organotin linker to a bodipy (BOD) photosensitizer. The relative potentials of the photosensitizer and POM are aligned such that light-induced electron transfer from BOD to POM is permitted for the polyoxomolybdate K-Sn(Mo)[BOD] but not effective for the polyoxotungstate analogue K-Sn(W)[BOD]. In both cases, the addition of acid shifts the redox potential of the POM only, to increase the driving force for electron transfer. This leads to charge-separation being switched on for K-Sn(W)[BOD] in the presence of acid. The addition of acid to K-Sn(Mo)[BOD] accelerates charge-separation by an order of magnitude (from 2 ns to 200 ps) and is accompanied by a deceleration of charge recombination, leading to a charge-separated state lifetime of up to 1.3 mu s. This behaviour is consistent with proton coupled electron transfer, which has previously been observed electrochemically for POMs, but this study shows, for the first time, the impact of protonation on photoinduced electron transfer.