Electric Fields in Catalysis: From Enzymes to Molecular Catalysts

Léonard, Nadia G.; Dhaoui, Rakia; Chantarojsiri, Teera; Yang, Jenny Y.

doi:10.1021/acscatal.1c02084

Cited by 89 publications

(82 citation statements)

References 143 publications

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“…Similar themes of electric field gradients enhancing reactivity are found in biology, where gradients in enzymes orient and break chemical bonds, or stabilize reaction intermediates. [59][60][61][62] In CO 2 electroreduction, a key intermediate is a bent negative radical form of CO 2 with a permanent dipole, which is highly unstable and requires breaking double bonds.…”

Section: Resultsmentioning

confidence: 99%

Tuning Ionic Screening to Accelerate Electrochemical CO2 Reduction in Ionic Liquid Electrolytes

Liu

Guo

Gebbie

2022

Preprint

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Electric double layer formation often governs the rate and selectivity of CO2 electrochemical reduction. Ionic correlations critically define double layer properties that are essential to electrocatalytic performance, including capacitance and localization of potential gradients. However, the influence of ionic correlations on CO2 electro-reduction remains unexplored. Here, we use electrochemical conversion of CO2 to CO in ionic liquid-based electrolytes to investigate how the emergence of ionic correlations with increasing ion concentration influences reaction rates and selectivity. Remarkably, we find substantial acceleration of potential-dependent CO2 reduction rates and notable enhancement of faradaic efficiency to CO at intermediate concentrations of 0.9 M ionic liquid in acetonitrile, a concentration regime that has not been studied previously. We find that onset potentials for CO2 reduction remain relatively unchanged at -2.01 V vs. Ag/Ag+ from 0.025 M up to 1.1 M and increase to -2.04 V vs. Ag/Ag+ in the limit of neat ionic liquids. Hence, the acceleration of CO2 reduction we observe originates from the amplification of potential-dependent driving forces, as opposed to changes in onset potential. Importantly, our findings are general across co-catalytic and non-catalytic ions. We propose that concentrations of maximum reactivity correspond to conditions where electric double layers exhibit the strongest screening, which would localize electric fields to stabilize polar intermediates. Our study demonstrates that tuning bulk electrostatic screening lengths via modulation of ionic clustering provides a general approach to accelerating both inner sphere and outer sphere electrochemical reactions.

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Section: Resultsmentioning

confidence: 99%

Tuning Ionic Screening to Accelerate Electrochemical CO2 Reduction in Ionic Liquid Electrolytes

Liu

Guo

Gebbie

2022

Preprint

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“…Electrostatic interactions dominate many aspects of macromolecular dynamics, frequently giving rise to important molecular phenomena, such as ion transport 1,2 or enzyme catalysis 3,4 . The molecular mechanisms behind such processes are subject of multiple investigations in both experimental and computational fields.…”

Section: Introductionmentioning

confidence: 99%

TUPÃ: Electric field analyses for molecular simulations

Polêto

Lemkul

2022

J Comput Chem

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We introduce TUPÃ, a Python‐based algorithm to calculate and analyze electric fields in molecular simulations. To demonstrate the features in TUPÃ, we present three test cases in which the orientation and magnitude of the electric field exerted by biomolecules help explain biological phenomena or observed kinetics. As part of TUPÃ, we also provide a PyMOL plugin to help researchers visualize how electric fields are organized within the simulation system. The code is freely available and can be obtained at https://mdpoleto.github.io/tupa/.

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“…The use of oriented internal electrostatic fields for impacting the binding, 1-3 activation, 1,2,4-8 and reactivity 7,[9][10][11][12][13][14][15][16] of small molecules is a rapidly emerging method for tuning the physical and chemical properties of metal complexes. 17,18 Internal electrostatic fields can be introduced into metal complexes either through incorporation of charged functional groups into ligands or through positioning of outer sphere ions, and they have been shown to be impactful in both ground state and catalytic contexts. A major challenge in characterizing these types of systems, however, comes in disentangling through-space electrostatic effects from more conventional electronic and steric effects (Figure 1).…”

Section: Introductionmentioning

confidence: 99%

Electrosteric Stabilization of End-on Cupric Superoxide Complexes

Weberg

McCollom

Tomson

2022

Preprint

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The use of oriented internal electrostatic fields in homogenous systems is rapidly gaining attention as a nonconventional design principle for imparting unusual properties and/or reactivity profiles on metal complexes and catalysts. Herein, a series of η1 cupric superoxide complexes bound by tris(phosphinimine) ligands (X-PhMe2P3tren) are reported. Across this series of complexes, the identity of the substituent at the 4 position of a phosphinimine phenyl group was modulated (X = NMe2, H, CF3). The X-PhMe2P3tren ligands impart systematic adjustments to the electronic and secondary coordination sphere electrostatic properties of the copper complexes while maintaining a consistent steric profile in the vicinity of the O2 binding pockets. Key differences in the thermal stabilities and proton-coupled electron transfer (PCET) kinetics were observed among the η1 cupric superoxide complexes, which are discussed in the context of both intra- and inter-molecular electrostatic interactions. Notably, the cupric superoxide complex that was most resistant to decomposition – [(CF3 PhMe2P3tren)CuII(O2•1–)]+ – displays markedly improved thermal stability compared to the Me3P3tren-bound cupric superoxide complex and can be observed as high as room temperature on a multi-minute timescale. Detailed kinetic and computational analyses suggest that the improved thermal stability in this context results from an electrosteric effect, in which the accumulation of cationic charge in the secondary coordination sphere slows bimolecular decomposition.

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Electric Fields in Catalysis: From Enzymes to Molecular Catalysts

Cited by 89 publications

References 143 publications

Tuning Ionic Screening to Accelerate Electrochemical CO2 Reduction in Ionic Liquid Electrolytes

Tuning Ionic Screening to Accelerate Electrochemical CO2 Reduction in Ionic Liquid Electrolytes

TUPÃ: Electric field analyses for molecular simulations

Electrosteric Stabilization of End-on Cupric Superoxide Complexes

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