Cationic Iridium Complexes Coordinated with Coumarin Dyes – Sensitizers for Visible‐Light‐Driven Hydrogen Generation
| Autor: | Shigeru Murata, Shin-ya Takizawa, Pavel Anzenbacher, Cesar Perez-Bolivar |
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| Rok vydání: | 2012 |
| Předmět: | |
| Zdroj: | European Journal of Inorganic Chemistry. 2012:3975-3979 |
| ISSN: | 1099-0682 1434-1948 |
| DOI: | 10.1002/ejic.201200474 |
| Popis: | Cationic iridium(III) complexes comprising two cyclometalating 3-(2-benzothiazolyl)-7-(diethylamino)coumarin (Coumarin 6) ligands and one diimine ancillary ligand (N N) were prepared [N N = 2,2′-bipyridyl (2), 1,10-phenanthroline (3), 2,2′-biquinoline (4)] and examined for their photophysical properties. The synergic effect of the intraligand charge-transfer (ILCT) transition in the chromophoric Coumarin 6 moiety and the metal-ligand-to-ligand CT (MLLCT) and/or ligand-to-ligand CT (LLCT) transitions associated with the diimine ligand rendered these complexes strongly absorptive in the visible region. Their enhanced absorptivity is significant when compared to the corresponding electroneutral complex 1 with acetylacetonate. Specifically, the molar extinction coefficient of complex 2 reached 129000 M–1 cm–1 at 483 nm, which is an unprecedentedly high value relative to those of other recently reported Ir-based dyes. Ir sensitizers 2–4 were tested for visible-light-driven hydrogen generation by using an Ir–Co photocatalytic system, where triethylamine and tris(2,2′-bipyridyl)dichloridocobalt were employed as a sacrificial electron donor and a water-reduction catalyst, respectively. As a result, complexes 2 and 3 were found to be highly effective sensitizers displaying turnover numbers up to 1500. |
| Databáze: | OpenAIRE |
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