Neutral Cyclometalated Ir(III) Complexes with Pyridylpyrrole Ligand for Photocatalytic Hydrogen Generation from Water

• Published in: Inorganic chemistry Vol. 60; no. 9; pp. 6266 - 6275
• Main Authors: Zhou, Yi, He, Piao, Mo, Xiu-Fang, Liu, Chao, Gan, Zhi-Liang, Tong, Hai-Xia, Yi, Xiao-Yi
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 03.05.2021
• ISSN: 0020-1669; 1520-510X
• DOI: 10.1021/acs.inorgchem.0c03812

To explore structure–activity relationships with respect to light-harvesting behavior, a family of neutral iridium complexes [Ir­(ppy)2(LR)] 1–4 (where ppy = 2-phenylpyridine, and N̂N = 2-(1H-pyrrol-2-yl)­pyridine and its functionalized derivatives) were designed and synthesized. The structural modifications in metal complexes are accomplished through the attributions of electron-donating CH3 in 2, OCH3 in 3, and electron-withdrawing CF3 in 4. The structural analysis displays that the pyridylpyrrole acts as one-negative charged bidentated ligand to chelate the iridium center. The electrochemical and photophysical properties of these complexes were systematically studied. The neutral 1–4 as well as the ionic structurally analogous [Ir­(ppy)2(bpy)]­(PF6) (5) were utilized as PSs in photocatalytic hydrogen generation from water with [Co­(bpy)3]­(PF6)2 as catalyst and triethanolamine (TEOA) as electron sacrificial agent in the presence of salt LiCl. Complex 1 maintains activity for more than 144 h under irradiation, and the total turnover number is up to 1768. The electrochemical properties and the quenching reaction indicate the H2 generation by neutral complexes 1–4 is involved exclusively in the oxidative quenching process.