On the role of noncovalent interactions in electrocatalysis. Two cases of mediated reductive dehalogenation

Romańczyk, Piotr P.; Noga, Klemens; Radoń, Mariusz; Rotko, Grzegorz; Kurek, Stefan S.

doi:10.1016/j.electacta.2013.05.006

Cited by 9 publications

(4 citation statements)

References 44 publications

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“…The direct reduction of HBCD at a carbon electrode in DMF was investigated by Baron et al , In addition, these researchers examined the reduction of HBCD in the presence of catalyst precursors such as cobalt tetraphenylporphyrin (CoTPP) and cobalamin; they discovered that the catalytic reduction of HBCD in the presence of CoTPP is more than 1 V easier than direct reduction. Romańczyk and co-workers used tetraphenylporphyrin as a procatalyst for the reduction of HBCD in dimethylformamide containing tetra- n -butylammonium tetrafluoroborate.…”

Section: Halogenated Environmental Pollutantsmentioning

confidence: 99%

Electroreductive Remediation of Halogenated Environmental Pollutants

et al. 2016

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Electrochemical reduction of halogenated organic compounds is gaining increasing attention as a strategy for the remediation of environmental pollutants. We begin this review by discussing key components (cells, electrodes, solvents, and electrolytes) in the design of a procedure for degrading a targeted pollutant, and we describe and contrast some experimental techniques used to explore and characterize the electrochemical behavior of that pollutant. Then, we describe how to probe various mechanistic features of the pertinent electrochemistry (including stepwise versus concerted carbon-halogen bond cleavage, identification of reaction intermediates, and elucidation of mechanisms). Knowing this information is vital to the successful development of a remediation procedure. Next, we outline techniques, instrumentation, and cell designs involved in scaling up a benchtop experiment to an industrial-scale system. Finally, the last and major part of this review is directed toward surveying electrochemical studies of various categories of halogenated pollutants (chlorofluorocarbons; disinfection byproducts; pesticides, fungicides, and bactericides; and flame retardants) and looking forward to future developments.

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Section: Halogenated Environmental Pollutantsmentioning

confidence: 99%

Electroreductive Remediation of Halogenated Environmental Pollutants

et al. 2016

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“…In the presence of CoTPP, the catalytic reduction of HBCD was more than 1 V easier than the direct reduction. In very recent research, Romańczyk and co-workers [152] have employed tetraphenylporphyrin as a procatalyst for the reduction of HBCD in DMF-TBABF 4 .…”

Section: Hexabromocyclododecanementioning

confidence: 99%

Electrochemical Dehalogenation of Organic Pollutants

et al. 2017

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<p>This review summarizes our own research, published since 2004, dealing with electrochemical reduction of halogenated organic compounds that are environmental pollutants. Included are sections surveying the direct and mediated reduction of the following species: (a) chlorofluorocarbons; (b) pesticides, fungicides, and bactericides; (c) flame retardants; and (d) disinfection by-products arising from the chlorination of water. To provide the reader with a perspective of these topics beyond our own work, a total of 238 literature citations, pertaining to studies conducted in numerous laboratories around the world, appears at the end of this review.</p>

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“…25 or -D3 26 variants) can efficiently cure this problem. [25][26][27] We used the B3LYP 28 hybrid functional because of its overall high accuracy and its good performance for predicting the structural and electronic properties of the {Mo(NO)Tp x } complexes we found previously. 29 Open-shell species were treated within the spinunrestricted scheme.…”

Section: Computational Detailsmentioning

confidence: 99%

“…35 The optimization was carried out at the dispersion-corrected DFT (DFT-D3) level, which is superior to ordinary DFT for these weakly bound solvates (see Computational details and ref. 27).…”

Section: Formation Of the {Mo IImentioning

confidence: 99%

Autocatalytic cathodic dehalogenation triggered by dissociative electron transfer through a C–H⋯O hydrogen bond

Romańczyk

Radoń

Noga

et al. 2013

Phys. Chem. Chem. Phys.

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A combined action of the C-H···Oalkoxide hydrogen bonding and Cl···πpyrazolyl dispersive interactions facilitates intramolecular electron transfer (ET) in the transient {Mo(I)(NO)(Tp(Me2))(Oalkoxide)}˙(-)···HCCl3 adduct ([Tp(Me2)](-) = κ(3)-hydrotris(3,5-dimethylpyrazol-1-yl)borate), setting off a radical autocatalytic process, eventually leading to chloroform degradation. In the voltammetric curve, this astonishingly fast process is seen as an almost vertical drop-down. The potential at which it occurs is favorably shifted by ca. 1 V in comparison with uncatalyzed reduction. As predicted by DFT calculations, crucial in the initial step is a close and prolonged contact between the electron donor (Mo(I) 4d-based SOMO) and acceptor (σ(*)(C-Cl)-based LUMO). This occurs owing to the exceptionally short (dH···O = 1.82 Å) and nearly linear C-H···Oalkoxide bonding, which is reflected by a large ΔνC-H red-shift of 380 cm(-1) and a noticeable reorganization of electronic density along the H-bond axis. The advantageous noncovalent interactions inside the cavity formed by two pyrazolyl (pz) rings are strengthened during the C-Cl bond elongation coupled with the ET, giving rise to possible transition state stabilization. After the initial period, the reaction proceeds as a series of consecutive alternating direct or Mo(II/I)-mediated electron and proton transfers. Alcohols inhibit the electrocatalysis by binding with the {Mo(I)-Oalkoxide}˙(-) active site, and olefins by trapping transient radicals. The proximity and stabilization effects, and competitive inhibition in the studied system may be viewed as analogous to those operating in enzymatic catalysis.

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On the role of noncovalent interactions in electrocatalysis. Two cases of mediated reductive dehalogenation

Cited by 9 publications

References 44 publications

Electroreductive Remediation of Halogenated Environmental Pollutants

Electroreductive Remediation of Halogenated Environmental Pollutants

Electrochemical Dehalogenation of Organic Pollutants

Autocatalytic cathodic dehalogenation triggered by dissociative electron transfer through a C–H⋯O hydrogen bond

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