Large Improvement in the Catalytic Activity Due to Small Changes in the Diimine Ligands: New Mechanistic Insight into the Dirhodium(II,II) Complex-Based Photocatalytic H2 Production
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- 作者：Jingfan Xie ; Chao Li ; Qianxiong Zhou ; Weibo Wang ; Yuanjun Hou ; Baowen Zhang ; Xuesong Wang
- 刊名：Inorganic Chemistry
- 出版年：2012
- 出版时间：June 4, 2012
- 年：2012
- 卷：51
- 期：11
- 页码：6376-6384
- 全文大小：536K
- 年卷期：v.51,no.11(June 4, 2012)
- ISSN：1520-510X
文摘
Two dirhodium(II) complexes, [RhII2(渭-O2CCH3)2(bpy)2](O2CCH3)2 (Rh2bpy2; bpy = 2,2鈥?bipyridine) and [RhII2(渭-O2CCH3)2(phen)2](O2CCH3)2 (Rh2phen2; phen = 1,10-phenanthroline) were synthesized, and their photocatalytic H2 production activities were studied in multicomponent systems, containing [IrIII(ppy)2(dtbbpy)]+ (ppy = 2-phenylpyridine, dtbbpy = 4,4鈥?di-tert-butyl-2,2鈥?bipyridine) as the photosensitizer (PS) and triethylamine as the sacrificial reductant (SR). There is a more than 6-fold increase in the photocatalytic activity from Rh2bpy2 to Rh2phen2 just using phen in place of bpy. A turnover number as high as 2622 was obtained after 50 h of irradiation of a system containing 16.7 渭M Rh2phen2, 50 渭M PS, and 0.6 M SR. The electrochemical, luminescence quenching, and transient absorption experiments demonstrate that RhIRhI is the true catalyst for the proton reduction. The real-time absorption spectra confirm that a new Rh-based species formed upon irradiation of the Rh2phen2-based multicomponent system, which exhibits an absorption centered at 575 nm. This 575-nm intermediate may account for the much higher H2 evolution efficiency of Rh2phen2. Our work highlights the importance of N-based chelate ligands and opens a new avenue for pursuing more efficient RhII2-based complexes in photocatalytic H2 production application.