AUTHOR=Kuramochi Yusuke , Ishitani Osamu 

TITLE=An Ir(III) Complex Photosensitizer With Strong Visible Light Absorption for Photocatalytic CO2 Reduction

JOURNAL=Frontiers in Chemistry

VOLUME=7

YEAR=2019

URL=https://www.frontiersin.org/journals/chemistry/articles/10.3389/fchem.2019.00259

DOI=10.3389/fchem.2019.00259

ISSN=2296-2646

ABSTRACT=<p>A cyclometalated iridium(III) complex having 2-(pyren-1-yl)-4-methylquinoline ligands [<bold>Ir(pyr)</bold>] has a strong absorption band in the visible region (ε<sub>444nm</sub> = 67,000 M<sup>−1</sup> cm<sup>−1</sup>) but does not act as a photosensitizer for photochemical reduction reactions in the presence of triethylamine as an electron donor. Here, 1,3-dimethyl-2-(o-hydroxyphenyl)-2,3-dihydro-1H-benzo[d]imidazole (BI(OH)H) was used instead of the amine, demonstrating that BI(OH)H efficiently quenched the excited state of <bold>Ir(pyr)</bold> and can undergo the photochemical carbon dioxide (CO<sub>2</sub>) reduction catalyzed by <italic>trans</italic>(Cl)-Ru(dmb)(CO)<sub>2</sub>Cl<sub>2</sub> (dmb = 4,4′-dimethyl-2,2′-bipyridine, <bold>Ru</bold>) to produce formate as the main product. We also synthesized a binuclear complex combining <bold>Ir(pyr)</bold> and <bold>Ru</bold><italic>via</italic> an ethylene bridge and investigated its photochemical CO<sub>2</sub> reduction activity in the presence of BI(OH)H.</p>