Fang Zhen, Ito Akitaka, Luo Hanlin, Ashford Dennis L, Concepcion Javier J, Alibabaei Leila, Meyer Thomas J
Department of Chemistry, University of North Carolina at Chapel Hill, CB3290, Chapel Hill, North Carolina 27599, USA.
Dalton Trans. 2015 May 14;44(18):8640-8. doi: 10.1039/c5dt00287g.
A Ru(II) polypyridyl-derivatized polypropylacrylate end-capped with a water-oxidation-catalyst (WOC) has been synthesized by using reversible addition-fragmentation chain transfer polymerization (RAFT) followed by click reaction and end-group functionalization. In cyclic voltammograms in propylene carbonate, chromophore oxidation occurs at 1.27 V vs. NHE and the Ru(III/II) wave for the catalyst at 0.84 V vs. NHE. Upon excitation of the Ru(II) chromophore, excited-state energy migration occurs by site-to-site, -Ru(II)- → -Ru(II)-, energy transfer hopping along the polymer chain, in part, reaching the terminal catalyst site where -Ru(II)- → -Ru(II)-OH2(2+) energy transfer is favored by ΔG(en) = -2100 cm(-1). Added MV(2+) as an electron transfer acceptor oxidizes the -Ru(II)- excited state on the polymer to Ru(III), -Ru(II)- + MV(2+) → -Ru(III)- + MV(+), and ultimately, the catalyst, by site-to-site electron transfer hopping and oxidation, [Formula: see text]. Oxidation is followed by relatively slow, diffusional back electron transfer from MV˙(+) to Ru(III) sites on the polymer chain. The mixed chromophore-catalyst polymer is a water oxidation catalyst with potential for enhanced light harvesting and water oxidation.
通过可逆加成-断裂链转移聚合（RAFT），随后进行点击反应和端基官能化，合成了一种末端带有水氧化催化剂（WOC）的钌（II）聚吡啶衍生聚丙烯酸酯。在碳酸丙烯酯中的循环伏安图中，发色团氧化发生在相对于标准氢电极（NHE）为1.27 V处，而催化剂的Ru(III/II)波出现在相对于NHE为0.84 V处。激发Ru(II)发色团后，激发态能量通过位点间迁移，即-Ru(II)- → -Ru(II)-，沿聚合物链进行能量转移跳跃，部分能量到达末端催化剂位点，在此处-Ru(II)- → -Ru(II)-OH2(2+)能量转移因ΔG(en) = -2100 cm(-1)而更有利。添加MV(2+)作为电子转移受体，将聚合物上的-Ru(II)-激发态氧化为Ru(III)，-Ru(II)- + MV(2+) → -Ru(III)- + MV(+)，最终通过位点间电子转移跳跃和氧化作用使催化剂发生[化学式：见原文]。氧化之后是相对较慢的、从MV˙(+)到聚合物链上Ru(III)位点的扩散性反向电子转移。这种混合发色团-催化剂聚合物是一种水氧化催化剂，具有增强光捕获和水氧化的潜力。
