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EnglishThe effect of phenyl, phenol, aniline, amino, and CF3 substituents of the 2,2′-bipyridine ligand in fac-ReCl(L)(CO)3 (L=2,2′-bipyridine derivative) catalysts on photochemical CO2 reduction in dimethylacetamide is examined, in order to understand the structure-function relationships and to compare the catalytic activities with the previously published electrochemical results. All complexes including ReCl(bpy)(CO)3 have similar excited-state lifetimes and emission spectra, but complex 1 with the Ph-NH2 moiety exhibits a significantly larger molar absorption coefficient for its metal-to-ligand charge transfer (MLCT) band. All complexes we tested produce CO with only a negligible amount of H2 and formate in self-sensitized systems in the presence of triethanolamine (TEOA) and in some cases, BIH (1,3-dimethyl-2-phenyl-2,3-dihydro-1H-benzo[d]-imidazole). The presence of the Ph-NH2 moiety (complex 1) has a beneficial effect on both electrochemical and photochemical activity, allowing a turnover number (TON) of 32 and 120 for photochemical CO production (without and with BIH, respectively). In the case of the Ph-OH group in the second coordination sphere (complexes 4 and 6), these complexes are active for photochemical CO2 reduction, despite the formation of a stable 6-coordinate Re-OPh intermediate via reductive deprotonation as previously observed under electrochemical conditions. Overall, BIH accelerates the rate of formation of the one-electron reduced species (OERS) of the Re catalysts and allows higher turnover frequency (TOF) and TON for CO formation. The X-ray structures of complexes 1 and 4 were determined to have distorted octahedral Re centres, and show π-π stacking interactions with neighboring molecules as well as intramolecular hydrogen bonds to the internal chloride ligands. The unusually high absorptivity of the MLCT absorption of complex 1 has been explained by TD-DFT calculations.
| Titolo: | Photochemical CO2 Reduction Using Rhenium(I) Tricarbonyl Complexes with Bipyridyl-Type Ligands with and without Second Coordination Sphere Effects | |
| Autori Riconosciuti: | ||
| Autori: | Rotundo L.; Grills D.C.; Gobetto R.; Priola E.; Nervi C.; Polyansky D.E.; Fujita E. | |
| Data di pubblicazione: | 2021 | |
| Abstract: | The effect of phenyl, phenol, aniline, amino, and CF3 substituents of the 2,2′-bipyridine ligand in fac-ReCl(L)(CO)3 (L=2,2′-bipyridine derivative) catalysts on photochemical CO2 reduction in dimethylacetamide is examined, in order to understand the structure-function relationships and to compare the catalytic activities with the previously published electrochemical results. All complexes including ReCl(bpy)(CO)3 have similar excited-state lifetimes and emission spectra, but complex 1 with the Ph-NH2 moiety exhibits a significantly larger molar absorption coefficient for its metal-to-ligand charge transfer (MLCT) band. All complexes we tested produce CO with only a negligible amount of H2 and formate in self-sensitized systems in the presence of triethanolamine (TEOA) and in some cases, BIH (1,3-dimethyl-2-phenyl-2,3-dihydro-1H-benzo[d]-imidazole). The presence of the Ph-NH2 moiety (complex 1) has a beneficial effect on both electrochemical and photochemical activity, allowing a turnover number (TON) of 32 and 120 for photochemical CO production (without and with BIH, respectively). In the case of the Ph-OH group in the second coordination sphere (complexes 4 and 6), these complexes are active for photochemical CO2 reduction, despite the formation of a stable 6-coordinate Re-OPh intermediate via reductive deprotonation as previously observed under electrochemical conditions. Overall, BIH accelerates the rate of formation of the one-electron reduced species (OERS) of the Re catalysts and allows higher turnover frequency (TOF) and TON for CO formation. The X-ray structures of complexes 1 and 4 were determined to have distorted octahedral Re centres, and show π-π stacking interactions with neighboring molecules as well as intramolecular hydrogen bonds to the internal chloride ligands. The unusually high absorptivity of the MLCT absorption of complex 1 has been explained by TD-DFT calculations. | |
| Volume: | 5 | |
| Fascicolo: | 6 | |
| Pagina iniziale: | 526 | |
| Pagina finale: | 537 | |
| Digital Object Identifier (DOI): | 10.1002/cptc.202000307 | |
| Parole Chiave: | carbon dioxide reduction; photocatalysis; reductive deprotonation; rhenium; structure-function relationships | |
| Rivista: | CHEMPHOTOCHEM | |
| Appare nelle tipologie: | 03A-Articolo su Rivista |
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| File | Descrizione | Tipologia | Licenza | |
|---|---|---|---|---|
| Photochemical paper_revisions.docx | POSTPRINT (VERSIONE FINALE DELL’AUTORE) | Open Access Visualizza/Apri | ||
| 113_Fujita-2021-Photochemical-co-reduction-using-r.pdf | PDF EDITORIALE | Utenti riconosciuti Richiedi una copia |
http://hdl.handle.net/2318/1802140
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