Copper Complexes of CF₃-Substituted Corroles for Affecting Redox Potentials and Electrocatalysis

Abstract

Electrocatalysis by first-row transition metals chelated by porphyrins, corroles, and related macrocycles gains increased attention due to the need of developing approaches for clean and renewable energy. While some of the above complexes display good catalytic activity, their performance often suffers from much larger overpotentials than the extremely efficient, but not sustainable metal, platinum. Intrigued by the report of copper corroles as catalysts for the electrochemical conversion of protons to hydrogen gas, we hypothesized that trifluoromethylation of corroles would be most effective for inducing a positive shift of the potentials required for reduction of the copper chelated thereby. A combination of methodologies allowed for full characterization of the trisand tetra-CF 3 -substituted complexes and elucidation of their unique structural, physical, and chemical properties. The desired outcome was also achieved, as the potential required for reduction to the copper(I) oxidation state, postulated to be the catalytically active species, was the least negative. The tris-substituted complex was found to be a particularly good electrocatalyst for production of hydrogen from protons, with a remarkably early catalytic onset potential.

Hydrogen evolution catalysis by terminal molybdenum-oxo complexes

“…Having demonstrated the facile access to low valent molybdenum metallocorroles, it attracts the interest to explore their interactions with small molecules and possible catalytic activation thereof. Effective hydrogen evaluation reaction (HER) from trifluoroacetic acid, acetic acid, acetonitrile/water, and neutral buffer solution solutions were recently reported by employing Fe IV , Co III , and Cu III corroles as electrocatalysts ( Chen et al., 2020 ; Lei et al., 2014 , 2015 ; Lin et al., 2020 ; Mahammed et al., 2014 ; Sudhakar et al., 2020 ; Sun et al., 2017 ; Zhong et al., 2019 ). On the other hand, there are no reports regarding HER catalysis by any (oxo)metal porphyrins or corroles despite of their rich redox chemistry.…”

“…Having demonstrated the facile access to low valent molybdenum metallocorroles, it attracts the interest to explore their interactions with small molecules and possible catalytic activation thereof. Effective hydrogen (Chen et al, 2020;Lei et al, 2014Lei et al, , 2015Lin et al, 2020;Mahammed et al, 2014;Sudhakar et al, 2020;Sun et al, 2017;Zhong et al, 2019). On the other hand, there are no reports regarding HER catalysis by any (oxo)metal porphyrins or corroles despite of their rich redox chemistry.…”

Augmented Magnetic Response and Spin-Transfer in Copper Corrole/Graphene Hybrids - A DFT Study

“…Cobalt corroles supported on graphene-based surfaces have improved catalytic performances towards hydrogen evolution [47] and oxygen reduction reaction [33]. This behavior is explained according to the strong π- interactions in the obtained hybrids, high stability, and the fast electron transfer on the hybrid.…”

“…1). The fluorinated substituents of the studied Cu corroles were selected since they promote the stability of the corrole structure and increase the formal high valent character of the metal center [33,37,47]. Furthermore, the nature of the substituents (noted R on Fig.…”

“…On the other hand, an increasing interest has been evidenced in the chemistry of corroles and their metallo-derivatives because of their unique photophysical and electrochemical properties [20][21][22]. Corroles are analogous to porphyrins but lacking the C20 meso-carbon atom at the core structure, and they have been proposed as suitable compounds in cancer therapy, sensing, organic electronics, and catalysis [23][24][25][26][27][28][29][30][31][32][33]. In this sense, new synthetic strategies for developing corrolic derivatives have been proposed, mainly substituted at the beta [23,34,35] and/or meso [23,35,36] positions of the corrolic core.…”