Kinetic and structural studies, origins of selectivity, and interfacial charge transfer in the artificial photosynthesis of CO

Smieja, Jonathan M.; Benson, Eric E.; Kumar, Bhupendra; Grice, Kyle A.; Seu, Candace S.; Miller, Alexander J. M.; Mayer, James M.; Kubiak, Clifford P.

doi:10.1073/pnas.1119863109

Cited by 195 publications

(266 citation statements)

References 27 publications

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“…Estimation of efficiency from the CV data was done by the he relative i cat /i p values (Table S1) following the method described in ref. 4,7 Comparing the current values detected in the CV at -2.24V (vs. Fc/Fc + ) recorded under CO 2 and N 2 atmosphere in acetonitrile/water laso show that the performance of 1-5 is comparable to one another, and is comparable to that of [Mn(CO) 3 (bpy)Br], at 30-60% efficiency. It is important that most sterically protected, MnDIPIMP and MnTBIEP, seem to be performing better as far as i cat /i p are concerned, but that the least sterically hindered MnIMP is the most efficient in the series.…”

Section: Estimation Of Electrocatalytic Activity Towards Co Productiomentioning

confidence: 99%

“…The recent demonstration of the electrocatalytic activity of manganese 2 analogues of the archetypal Re(I) catalysts 3,4,5,6 for CO 2 reduction has given a new impetus to research into noble-metal-free catalytic systems. [MnBr(CO) 3 ( -diimine)] complexes have been shown to outperform rhenium-based analogues with regard to CO 2 reduction under certain conditions.…”

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confidence: 99%

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Manganese Tricarbonyl Complexes with Asymmetric 2-Iminopyridine Ligands: Toward Decoupling Steric and Electronic Factors in Electrocatalytic CO₂ Reduction

et al. 2016

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Manganese tricarbonyl bromide complexes incorporating IP (2-[(phenylimino)]pyridine) derivatives, [MnBr(CO) 3 (IP)], are demonstrated as a new group of catalysts for CO 2 reduction, which represent the first example of utilization of phenylimino pyridine ligands on manganese centers for this purpose. The key feature is the asymmetric structure of the redox non-innocent ligand that permits independent tuning of its steric and electronic properties. The -diimine ligands and five new Mn(I) compounds have been synthesized, isolated in high yields and fully characterized, including X-ray crystallography. Their electrochemical and electrocatalytic behavior was investigated using cyclic voltammetry and UV-vis /IR spectroelectrochemistry within an OTTLE cell. Mechanistic investigations under an inert atmosphere have revealed differences in the nature of the reduction products as a function of steric bulk of the ligand. The direct ECE (electrochemical-chemical-electrochemical) formation of a five-coordinate anion [Mn(CO) 3 (IP)] -, a product of 2-electron reduction of the parent complex, is observed in case of the bulky The interest in solar fuels in terms of both photocatalytic and electrocatalytic CO 2 reduction 1 , in the latter case utilizing sustainable electricity, has been increasing markedly in the new millennium. The recent demonstration of the electrocatalytic activity of manganese 2 analogues of the archetypal Re(I) catalysts 3,4,5,6 for CO 2 reduction has given a new impetus to research into noble-metal-free catalytic systems. [MnBr(CO) 3 ( -diimine)] complexes have been shown to outperform rhenium-based analogues with regard to CO 2 reduction under certain conditions. 7 Most notably, the presence of a Brönsted acid 7-10 appears to be a prerequisite for catalysis with a range of tricarbonyl Mndiimine complexes. Mechanistic studies 5,10 of the active 2,2 -bipyridine-based (Rbpy) manganese catalysts have shown that one-electron reduction of the parent complex [MnBr(CO) 3 (R-bpy)] precursor results in the formation of the Mn Mn dimer [Mn(CO) 3 (Rbpy)] 2 . 8,9 Notably, neither the primary reduction product [MnBr(CO) 3 (R-bpy )] nor the five-coordinate radical intermediates [Mn(CO) 3 (R-bpy)] have been detected by either UV-vis or IR spectroscopy. 2,7 Nanosecond time-resolved infrared (TRIR) studies reveal that no detectable solvent adduct is formed before the dimerization of Mn species on this timescale; instead, the five-coordinate species is observed, which rapidly dimerises. 10 For some of the Re analogues, a one-electron reduced complex, [ReCl(CO) 3 (R-bpy )] was observed by IR spectroscopy and identified by the ca. 15-20 cm -1 decrease in the (CO) energy, 11,12,13 as was the five-coordinate radical [Re(CO) 3 ( t Bubpy)] by an additional 15-20 cm -1 shift .Two mechanisms have been proposed 10,14-18 for the ultimate reduction of [Mn(CO) 3 ( -diimine)] 2 in the presence of CO 2 , which can be referred to as the anionic, and the oxidative addition 19 pathways. The anionic pathway involves reduction of ...

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Section: Estimation Of Electrocatalytic Activity Towards Co Productiomentioning

confidence: 99%

mentioning

confidence: 99%

Manganese Tricarbonyl Complexes with Asymmetric 2-Iminopyridine Ligands: Toward Decoupling Steric and Electronic Factors in Electrocatalytic CO₂ Reduction

et al. 2016

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“…Renewable production of carbon-based fuels can be accomplished by interfacing electrocatalysts for CO 2 reduction with a photovoltaic assembly 8–10 or a conventional electrolyzer powered by an alternative source of electricity. Of the several major classes of homogenous electrocatalysts for CO 2 reduction, 11 metal polypyrridyl complexes based on ruthenium, 12–17 and rhenium 18–25 have been particularly well studied.…”

Section: Introductionmentioning

confidence: 99%

Reduction of CO2 using a rhenium bipyridine complex containing ancillary BODIPY moieties

et al. 2014

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The reduction of carbon dioxide to chemical fuels such as carbon monoxide is an important challenge in the field of renewable energy conversion. Given the thermodynamic stability of carbon dioxide, it is difficult to efficiently activate this substrate in a selective fashion and the development of new electrocatalysts for CO2 reduction is of prime importance. To this end, we have prepared and studied a new fac-ReI(CO)3 complex supported by a bipyridine ligand containing ancillary BODIPY moieties ([Re(BB2)(CO)3Cl]). Voltammetry experiments revealed that this system displays a rich redox chemistry under N2, as [Re(BB2)(CO)3Cl] can be reduced by up to four electrons at modest potentials. These redox events have been characterized as the ReI/0 couple, and three ligand based reductions – two of which are localized on the BODIPY units. The ability of the BB2 ligand to serve as a non-innocent redox reservoir is manifest in an enhanced electrocatalysis with CO2 as compared to an unsubstituted Re-bipyridine complex lacking BODIPY units ([Re(bpy)(CO)3Cl]). The second order rate constant for reduction of CO2 by [Re(BB2)(CO)3Cl] was measured to be k = 3400 M−1s−1 at an applied potential of −2.0 V versus SCE, which is roughly three times greater than the corresponding unsubstituted Re-bipyridine homologue. Photophysical and photochemical studies were also carried out to determine if [Re(BB2)(CO)3Cl] was a competent platform for CO2 reduction using visible light. These experiments showed that this complex supports unusual excited state dynamics that precludes efficient CO2 reduction and are distinct from those that are typically observed for fac-ReI(CO)3 complexes.

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“…It is important for catalysts to be flexible to accommodate different conformations to facilitate reactions. 51 Thus, an optimized anchoring group selection could exist to balance the charge transfer rate, and the flexibility of catalysts. Our work shows the potential of using HD 2D SFG to assess the flexibility of the surface catalysts.…”

Section: D1=0364±0008 and D2=014±002mentioning

confidence: 99%

Solving the “Magic Angle” Challenge in Determining Molecular Orientation Heterogeneity at Interfaces

Xiong

2016

J. Phys. Chem. C

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It is critical to determine conformations of molecular monolayers in order to understand and control their functions and properties, such as efficiencies of self-assembly-based biosensors and turnover frequency of surface-bound electrocatalysts. However, surface molecules of the monolayers can adopt conformations with many different orientations. Thus, it is necessary to describe the orientations of surface molecular monolayers using both mean tilt angle and orientational distribution, which together we refer as orientation heterogeneity. Orientation heterogeneity is difficult to measure. In most cases, in order to calculate the mean tilt angle, it is assumed that the orientational distribution is narrow. This assumption causes ambiguities in determining the mean tilt angle, and loss of orientational distribution information, which is known as the "magic angle" challenge. Using heterodyne two-dimensional vibrational sum frequency generation (HD 2D VSFG) spectroscopy, we report a novel method to solve the "magic angle" challenge, by simultaneously measuring mean tilt angle and orientational distribution of molecular monolayers. We applied this new method to a CO2 reduction catalyst/gold interface and found that the catalysts formed a monolayer with a mean tilt angle between its quasi-C3 symmetric axis and the surface normal of 53°, with 5° orientational distribution. The narrow orientational distribution indicates that the surface molecules are rigid, which sample only limited configurations for facilitating a reaction, because of the short anchoring groups. Although applied to a specific system, this method is a general way to determine the orientation heterogeneity of an ensemble-averaged molecular interface.3

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Kinetic and structural studies, origins of selectivity, and interfacial charge transfer in the artificial photosynthesis of CO

Cited by 195 publications

References 27 publications

Manganese Tricarbonyl Complexes with Asymmetric 2-Iminopyridine Ligands: Toward Decoupling Steric and Electronic Factors in Electrocatalytic CO₂ Reduction

Manganese Tricarbonyl Complexes with Asymmetric 2-Iminopyridine Ligands: Toward Decoupling Steric and Electronic Factors in Electrocatalytic CO₂ Reduction

Reduction of CO2 using a rhenium bipyridine complex containing ancillary BODIPY moieties

Solving the “Magic Angle” Challenge in Determining Molecular Orientation Heterogeneity at Interfaces

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Kinetic and structural studies, origins of selectivity, and interfacial charge transfer in the artificial photosynthesis of CO

Cited by 195 publications

References 27 publications

Manganese Tricarbonyl Complexes with Asymmetric 2-Iminopyridine Ligands: Toward Decoupling Steric and Electronic Factors in Electrocatalytic CO2 Reduction

Manganese Tricarbonyl Complexes with Asymmetric 2-Iminopyridine Ligands: Toward Decoupling Steric and Electronic Factors in Electrocatalytic CO2 Reduction

Reduction of CO2 using a rhenium bipyridine complex containing ancillary BODIPY moieties

Solving the “Magic Angle” Challenge in Determining Molecular Orientation Heterogeneity at Interfaces

Contact Info

Product

Resources

About

Manganese Tricarbonyl Complexes with Asymmetric 2-Iminopyridine Ligands: Toward Decoupling Steric and Electronic Factors in Electrocatalytic CO₂ Reduction

Manganese Tricarbonyl Complexes with Asymmetric 2-Iminopyridine Ligands: Toward Decoupling Steric and Electronic Factors in Electrocatalytic CO₂ Reduction