Ligand−Structure Effects on N−Heterocyclic Carbene Rhenium Photo− and Electrocatalysts of CO2 Reduction

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F60461373%3A22310%2F23%3A43926238" target="_blank" >RIV/60461373:22310/23:43926238 - isvavai.cz</a>

Result on the web

<a href="https://www.mdpi.com/1420-3049/28/10/4149" target="_blank" >https://www.mdpi.com/1420-3049/28/10/4149</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.3390/molecules28104149" target="_blank" >10.3390/molecules28104149</a>

Result language

angličtina

Original language name

Ligand−Structure Effects on N−Heterocyclic Carbene Rhenium Photo− and Electrocatalysts of CO2 Reduction

Original language description

Three novel rhenium N−heterocyclic carbene complexes, [Re]−NHC−1−3 ([Re] = fac−Re(CO)3Br), were synthesized and characterized using a range of spectroscopic techniques. Photophysical, electrochemical and spectroelectrochemical studies were carried out to probe the properties of these organometallic compounds. Re−NHC−1 and Re−NHC−2 bear a phenanthrene backbone on an imidazole (NHC) ring, coordinating to Re by both the carbene C and a pyridyl group attached to one of the imidazole nitrogen atoms. Re−NHC−2 differs from Re−NHC−1 by replacing N−H with an N−benzyl group as the second substituent on imidazole. The replacement of the phenanthrene backbone in Re−NHC−2 with the larger pyrene gives Re−NHC−3. The two−electron electrochemical reductions of Re−NHC−2 and Re−NHC−3 result in the formation of the five−coordinate anions that are capable of electrocatalytic CO2 reduction. These catalysts are formed first at the initial cathodic wave R1, and then, ultimately, via the reduction of Re−Re bound dimer intermediates at the second cathodic wave R2. All three Re−NHC−1−3 complexes are active photocatalysts for the transformation of CO2 to CO, with the most photostable complex, Re−NHC−3, being the most effective for this conversion. Re−NHC−1 and Re−NHC−2 afforded modest CO turnover numbers (TONs), following irradiation at 355 nm, but were inactive at the longer irradiation wavelength of 470 nm. In contrast, Re−NHC−3, when photoexcited at 470 nm, yielded the highest TON in this study, but remained inactive at 355 nm. The luminescence spectrum of Re−NHC−3 is red−shifted compared to those of Re−NHC−1 and Re−NHC−2, and previously reported similar [Re]−NHC complexes. This observation, together with TD−DFT calculations, suggests that the nature of the lowest−energy optical excitation for Re−NHC−3 has π→π*(NHC−pyrene) and dπ(Re)→π*(pyridine) (IL/MLCT) character. The stability and superior photocatalytic performance of Re−NHC−3 are attributed to the extended conjugation of the π−electron system, leading to the beneficial modulation of the strongly electron−donating tendency of the NHC group. © 2023 by the authors.

Czech name

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Czech description

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Type

J_imp - Article in a specialist periodical, which is included in the Web of Science database

CEP classification

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OECD FORD branch

10405 - Electrochemistry (dry cells, batteries, fuel cells, corrosion metals, electrolysis)

Project

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Continuities

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Publication year

2023

Confidentiality

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Name of the periodical

Molecules

ISSN

1420-3049

e-ISSN

1420-3049

Volume of the periodical

28

Issue of the periodical within the volume

10

Country of publishing house

CH - SWITZERLAND

Number of pages

23

Pages from-to

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UT code for WoS article

000997745800001

EID of the result in the Scopus database

2-s2.0-85160373145