Department of Chemistry , University of North Carolina at Chapel Hill , Chapel Hill , North Carolina 27599 , United States.
Chem Rev. 2019 Apr 10;119(7):4628-4683. doi: 10.1021/acs.chemrev.8b00732. Epub 2019 Mar 11.
Halide photoredox chemistry is of both practical and fundamental interest. Practical applications have largely focused on solar energy conversion with hydrogen gas, through HX splitting, and electrical power generation, in regenerative photoelectrochemical and photovoltaic cells. On a more fundamental level, halide photoredox chemistry provides a unique means to generate and characterize one electron transfer chemistry that is intimately coupled with X-X bond-breaking and -forming reactivity. This review aims to deliver a background on the solution chemistry of I, Br, and Cl that enables readers to understand and utilize the most recent advances in halide photoredox chemistry research. These include reactions initiated through outer-sphere, halide-to-metal, and metal-to-ligand charge-transfer excited states. Kosower's salt, 1-methylpyridinium iodide, provides an early outer-sphere charge-transfer excited state that reports on solvent polarity. A plethora of new inner-sphere complexes based on transition and main group metal halide complexes that show promise for HX splitting are described. Long-lived charge-transfer excited states that undergo redox reactions with one or more halogen species are detailed. The review concludes with some key goals for future research that promise to direct the field of halide photoredox chemistry to even greater heights.
卤化物光氧化还原化学具有实际和基础研究的双重意义。实际应用主要集中在太阳能转化为氢气，通过 HX 裂解，以及在可再生光电化学和光伏电池中发电。在更基础的层面上，卤化物光氧化还原化学提供了一种独特的方法来产生和表征与 X-X 键的断裂和形成反应密切相关的单电子转移化学。本综述旨在介绍 I、Br 和 Cl 的溶液化学，使读者能够理解和利用卤化物光氧化还原化学研究的最新进展。这些进展包括通过外层、卤化物到金属和金属到配体电荷转移激发态引发的反应。Kosower 盐，1-甲基吡啶碘化物，提供了一个早期的外层电荷转移激发态，可以报告溶剂极性。描述了大量基于过渡金属和主族金属卤化物配合物的新型内壳层配合物，这些配合物有望用于 HX 裂解。详细介绍了经历与一个或多个卤化物物种的氧化还原反应的长寿命电荷转移激发态。该综述以未来研究的一些关键目标结束，这些目标有望将卤化物光氧化还原化学领域推向更高的水平。
