DiLuzio Stephen, Baumer Mitchell, Guzman Rafael, Kagalwala Husain, Lopato Eric, Talledo Savannah, Kangas Joshua, Bernhard Stefan
Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States.
Inorg Chem. 2024 Aug 5;63(31):14267-14277. doi: 10.1021/acs.inorgchem.4c02420. Epub 2024 Jul 20.
High-throughput synthesis and screening (HTSS) methods were used to investigate the photophysical properties of 576 heteroleptic Rh(III) transition-metal complexes through measurement of the UV-visible absorption spectra, deaerated excited-state lifetime, and phosphorescent emission spectra. While 4d transition-metal photophysics are often highly influenced by deleterious metal-centered deactivation channels, the HTSS of structurally diverse cyclometalating and ancillary ligands attached to the metal center facilitated the discovery of photoactive complexes exhibiting long-lived charge-transfer phosphorescence (0.15-0.95 μs) spanning a substantial portion of the visible region (546-620 nm) at room temperature. Further photophysical and electrochemical investigations were then carried out on select complexes with favorable photophysics to understand the underlying features controlling these superior properties. Heteroleptic Ir(III) complexes with identical ligand morphology were also synthesized to compare these features to this family of well understood chromophores. A number of these Rh(III) complexes contained the requisite properties for photocatalytic activity and were consequently tested as photocatalysts (PCs) in a water reduction system using a Pd water reduction cocatalyst. Under certain conditions, the activity of the Rh(III) PC actually surpassed that of the Ir(III) PC, uncovering the potential of this often-overlooked class of transition metals as both efficient photoactive chromophores and PCs.
采用高通量合成与筛选（HTSS）方法，通过测量紫外可见吸收光谱、除气激发态寿命和磷光发射光谱，研究了576种杂配铑（III）过渡金属配合物的光物理性质。虽然4d过渡金属的光物理性质常常受到有害的以金属为中心的失活通道的强烈影响，但对连接在金属中心上的结构多样的环金属化配体和辅助配体进行高通量合成，有助于发现室温下具有长寿命电荷转移磷光（0.15 - 0.95微秒）的光活性配合物，其磷光覆盖了可见光区域（546 - 620纳米）的很大一部分。然后，对具有良好光物理性质的选定配合物进行了进一步的光物理和电化学研究，以了解控制这些优异性质的潜在特征。还合成了具有相同配体形态的杂配铱（III）配合物，以便将这些特征与这一类已被充分了解的发色团进行比较。其中许多铑（III）配合物具备光催化活性所需的性质，因此在使用钯水还原助催化剂的水还原体系中作为光催化剂（PCs）进行了测试。在某些条件下，铑（III）光催化剂的活性实际上超过了铱（III）光催化剂，揭示了这类常被忽视的过渡金属作为高效光活性发色团和光催化剂的潜力。
