Solar Light CO₂ Photoreduction Enhancement by Mononuclear Rhenium(I) Complexes: Characterization and Mechanistic Insights

resumo

The catalytic efficacy of a novel mononuclear rhenium(I) complex in CO2 reduction is remarkable, with a turnover number (TONCO) of 1517 in 3 h, significantly outperforming previous Re(I) catalysts. This complex, synthesized via a substitution reaction on an aromatic ring to form a bromo-bipyridine derivative, L1 = 2-bromo-6-(1H-pyrazol-1-yl)pyridine, and further reacting with [Re(CO)(5)Cl], results in the facial-tricarbonyl complex [ReL1(CO)(3)Cl] (1). The light green solid was obtained with an 80% yield and thoroughly characterized using cyclic voltammetry, nuclear magnetic resonance (NMR), Fourier transform infrared (FTIR) spectroscopy, and ultraviolet-visible (UV-vis) spectroscopy. Cyclic voltammetry under CO2 atmosphere revealed three distinct redox processes, suggesting the formation of new electroactive compounds. The studies on photoreduction highlighted the ability of the catalyst to reduce CO2, while NMR, FTIR, and electrospray ionization (ESI) mass spectrometry provided insights into the mechanism, revealing the formation of solvent-coordinated complexes and new species under varying conditions. Additionally, computational studies (DFT) were undertaken to better understand the electronic structure and reactivity patterns of 1, focusing on the role of the ligand, the spectroscopic features, and the redox behavior. This comprehensive approach provides insights into the intricate dynamics of CO2 photoreduction, showcasing the potential of Re(I) complexes in catalysis.

palavras-chave

CARBON-DIOXIDE; ELECTROCATALYTIC REDUCTION; PHOTOINDUCED REDUCTION; METAL-COMPLEXES; VISIBLE-LIGHT; CATALYST; CONVERSION; BINUCLEAR; LIGANDS; CAPTURE

categoria

Chemistry

autores

Bento, MA; Bandeira, NAG; Miras, HN; Moro, AJ; Lima, JC; Realista, S; Gleeson, M; Devid, EJ; Brandao, P; Rocha, J; Martinho, PN

Grupos

G1 - Materiais Porosos e Nanossistemas

Projectos

CICECO - Aveiro Institute of Materials (UIDB/50011/2020)

CICECO - Aveiro Institute of Materials (UIDP/50011/2020)

Associated Laboratory CICECO-Aveiro Institute of Materials (LA/P/0006/2020)

agradecimentos

Centro de Quimica Estrutural (CQE) and Institute of Molecular Sciences (IMS) acknowledge the financial support of Fundacao para a Ciencia e Tecnologia (Projects UIDB/00100/2020: 10.54499/UIDB/00100/2020, UIDP/00100/2020: 10.54499/UIDP/00100/2020, and LA/P/0056/2020: 10.54499/LA/P/0056/2020, respectively). BioISI acknowledges FCT for financial support (UIDB/04046/2020, UIDP/04046/2020). P.N.M. thanks FCT for financial support (grant PTDC/QUI-QIN/0252/2021: 10.54499/PTDC/QUI-QIN/0252/2021 and contract CEECIND/00509/2017: 10.54499/CEECIND/00509/2017/CP1387/CT0029). S.R. thanks FCT for the contract 2020.02134.CEECIND: 10.54499/2020.02134.CEECIND/CP1605/CT0002. M.A.B. thanks FCT for the PhD scholarship (2021.07918.BD: 10.54499/2021.07918.BD). N.A.G.B. gratefully acknowledges Prof. Frank Neese for providing access to computational infrastructure and the FCT/DL57 researcher program for funding (doi: 10.54499/DL57/2016/CP1479/CT0050). E.J.D. thanks Richard van de Sanden from DIFFER for support and fruitful discussions. H.N.M. thanks EPSRC (EP/R01308X/1) and the University of Glasgow for supporting this work, and Prof. L. Cronin for providing access to the ESI-MS instrumentation. J.R. thanks the project CICECO-Aveiro Institute of Materials, UIDB/50011/2020, UIDP/50011/2020 & LA/P/0006/2020, financed by national funds through the FCT/MCTES (PIDDAC). LAQV-REQUIMTE acknowledges FCT-MCTES for financial support (UIDB/50006/2020 and UIDP/50006/2020). COST Actions CA21101 (COSY), CA21127 (TrANsMIT), and CA22131 (LUCES) are also acknowledged.