Photocatalytic reduction of CO2 to CO by a dinuclear carbonyl polypyridyl rhenium(I) complex

1IL and 3MLCT excited states modulated by H+: the structure and photophysical properties of [(2-bromo-5-(1H-pyrazol-1-yl)pyrazine)Re(CO)3Br]

The photophysical characterization of pyrazolyl–pyrazine Re(i) complex, shows a ¹IL and ³MLCT excited states, being just the ³MLCT able to react with trifluoroacetic acid to yield the protonated and long-lived ³ILH⁺ species. These findings make the compound a potential sensor for protons in solution in the presence of light.

Photochemical CO2 reduction with mononuclear and dinuclear rhenium catalysts bearing a pendant anthracene chromophore

Well-defined dinuclear rhenium photocatalysts featuring an anthracene chromophore are significantly faster and more durable than their mononuclear counterparts.

Electrocatalytic CO2 Reduction with Cis and Trans Conformers of a Rigid Dinuclear Rhenium Complex: Comparing the Monometallic and Cooperative Bimetallic Pathways

Anthracene-bridged dinuclear rhenium complexes are reported for electrocatalytic carbon dioxide (CO₂) reduction to carbon monoxide (CO). Related by hindered rotation of each rhenium active site to either side of the anthracene bridge, cis and trans conformers have been isolated and characterized. Electrochemical studies reveal distinct mechanisms, whereby the cis conformer operates via cooperative bimetallic CO₂ activation and conversion and the trans conformer reduces CO₂ through well-established single-site and bimolecular pathways analogous to Re(bpy)(CO)₃Cl. Higher turnover frequencies are observed for the cis conformer (35.3 s^-1) relative to the trans conformer (22.9 s^-1), with both outperforming Re(bpy)(CO)₃Cl (11.1 s^-1). Notably, at low applied potentials, the cis conformer does not catalyze the reductive disproportionation of CO₂ to CO and CO₃^2- in contrast to the trans conformer and mononuclear catalyst, demonstrating that the orientation of active sites and structure of the dinuclear cis complex dictate an alternative catalytic pathway. Further, UV-vis spectroelectrochemical experiments demonstrate that the anthracene bridge prevents intramolecular formation of a deactivated Re-Re-bonded dimer. Indeed, the cis conformer also avoids intermolecular Re-Re bond formation.

The Mechanism of Room-Temperature Ionic-Liquid-Based Electrochemical CO₂ Reduction: A Review

Electrochemical CO₂ conversion technology is becoming indispensable in the development of a sustainable carbon-based economy. While various types of electrocatalytic systems have been designed, those based on room-temperature ionic liquids (RTILs) have attracted considerable attention because of their high efficiencies and selectivities. Furthermore, it should be possible to develop more advanced electrocatalytic systems for commercial use because target-specific characteristics can be fine-tuned using various combinations of RTIL ions. To achieve this goal, we require a systematic understanding of the role of the RTIL components in electrocatalytic systems, however, their role has not yet been clarified by experiment or theory. Thus, the purpose of this short review is to summarize recent experimental and theoretical mechanistic studies to provide insight into and to develop guidelines for the successful development of new CO₂ conversion systems. The results discussed here can be summarized as follows. Complex physical and chemical interactions between the RTIL components and the reaction intermediates, in particular at the electrode surface, are critical for determining the activity and selectivity of the electrocatalytic system, although no single factor dominates. Therefore, more fundamental research is required to understand the physical, chemical, and thermodynamic characteristics of complex RTIL-based electrocatalytic systems.

Contrasting photophysical properties of rhenium(i) tricarbonyl complexes having carbazole groups attached to the polypyridine ligand

The fac-[Re(CO)₃(cbz₂phen)(L)]^0/+1 complexes showed a remarkable presence of the ILCT_cbz2phen fluorescence in addition to the usually observed ³MLCT_{Re→cbz2phen}. In PMMA films the emission is completely turned into a triplet excited state manifold.

Electrocatalytic reduction of CO2 to CO by a mononuclear ruthenium(ii) complex

A new mononuclear ruthenium(ii) complex, [Ru(dmbpy)(tptz)(Cl)](PF₆) (where dmbpy = 4,4′-dimethyl-2,2′-bipyridine and tptz = 2,4,6-tris(2-pyridyl)-1,3,5-triazine), has been prepared and characterized by spectroscopic methods, cyclic voltammetry (CV), and single-crystal X-ray crystallography.

Photoreduction of CO2 to CO by a mononuclear Re(i) complex and DFT evaluation of the photocatalytic mechanism

A new method for the preparation of fac-[Re(phen-dione)(CO)₃Cl] and its application for the photochemical reduction of CO₂ to CO have been reported.