Tuning the Formal Potential of Metallomacrocyclics for Maximum Catalytic Activity For the Oxidation of Thiols and Hydrazine

Ochoa, Gonzalo; Geraldo, Daniela A.; Linares, Cristian; Nyokong, Tebello; Bédioui, Féthi; Zagal, José H.

doi:10.1149/1.3268166

Cited by 7 publications

(3 citation statements)

References 49 publications

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“…These results are in agreement with previous theoretical studies of the effect of the substituent in zinc porphyrin monomers. , In porphyrinoid systems, the redox-potential shifts are linearly correlated with the Hammett parameters of the peripheral substituents. Electron-donating groups make the redox potential more negative, and electron-withdrawing groups make the redox potential more positive . Therefore, systems with electron-donating substituents might transfer electrons easily, that is, the occupied orbitals display higher energies relative to macrocycles with electron-withdrawing groups.…”

Section: Resultsmentioning

confidence: 99%

“…Electron-donating groups make the redox potential more negative, and electronwithdrawing groups make the redox potential more positive. 49 Therefore, systems with electron-donating substituents might transfer electrons easily, that is, the occupied orbitals display higher energies relative to macrocycles with electron-withdrawing groups.…”

Section: ■ Computational Methodsmentioning

confidence: 99%

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Theoretical Study of Sensitizer Candidates for Dye-Sensitized Solar Cells: Peripheral Substituted Dizinc Pyrazinoporphyrazine–Phthalocyanine Complexes

et al. 2013

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We have carried out a theoretical study of the geometrical and electronic structures of a family of planar dimers constituted by zinc(II) pyrazinoporphyrazine and zinc(II) phthalocyanine with peripheral electron-donating and electron-withdrawing substituents R [where R = -OH (1), -C(CH(3))(3) (2), -CH(3) (3), -C(6)H(5) (4), -H (5), -CO(2)H (7), -NO(2) (7), and -PO(3)H(2) (8)]. The complexes are connected by varying the bridge (B) ligand, where, in 1-9, B is -CH= and, in 10-12, B is -N=, -O-, and -S-, respectively. The -CO(2)H group was included in complexes identified as 9-12. This was done because of the known properties of this group in acting as an anchor to adsorb a dye onto a semiconductor oxide. The aim of this work was to provide a useful theoretical basis for the design and screening of new potential dye candidates to be used in these devices, based on the properties of the dyes suitable for their good performance in solar cells, such as frontier molecular orbital spatial distributions; charge-separated states in the electronic transitions in the visible region of the spectrum; and importantly, the energy diagram of the frontier MOs of these dyes and the conduction band (CB) of the semiconductor, where the LUMO energy levels that are above of the CB suggest which dyes are capable of electron injection into TiO(2). In this sense, it is expected that complexes 1-5 and 9-12 should be very promising dyes to act as sensitizers. Finally, a linear correlation was found between the HOMO and LUMO energies of all of the systems and the Hammett constants, where these molecular orbitals become more stable when R is more electron-withdrawing.

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Section: Resultsmentioning

confidence: 99%

Section: ■ Computational Methodsmentioning

confidence: 99%

Theoretical Study of Sensitizer Candidates for Dye-Sensitized Solar Cells: Peripheral Substituted Dizinc Pyrazinoporphyrazine–Phthalocyanine Complexes

et al. 2013

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“…Hollow spheres indicate different surface concentrations. Adapted with permission from refs , , , , and .…”

Section: Molecular Electrocatalysts: the Hunt For Reactivity Descriptorsmentioning

confidence: 99%

Hydrazine Oxidation Electrocatalysis

Burshtein,

Yasman,

Muñoz-Moene

et al. 2024

ACS Catal.

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The electro-oxidation of hydrazine is important for direct hydrazine fuel cells and for fundamental understanding of electrocatalysis in the nitrogen cycle. In this Review, we discuss electrocatalysis of the hydrazine oxidation reaction (HzOR), spanning a vast range of metal surfaces, nanoparticles, atomically dispersed ions, organometallic macrocycles, and enzymes. Emphasis is given to structure−activity correlations and reactivity descriptors, including the formulation of the Zagal principle, an electrochemical corollary of the Sabatier principle. In addition, we identify overarching themes that span the different subfields of HzOR electrocatalysis, hoping to inspire cross-disciplinary research avenues.

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Optimizing the Electrocatalytic Activity of Surface Confined Co Macrocyclics for the Electrooxidation of Thiocyanate at pH 4

et al. 2011

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We have studied the trends in catalytic activity of several Co macrocyclics confined on the surface graphite electrodes for the oxidation of thiocyanate. A plot of log i (at constant E) versus the formal potential of the catalyst gives a volcano correlation, indicating that the Co(II/I) redox potential needs to be tuned, in order to achieve maximum reactivity. Graphite electrodes modified with Co phthalocyanine at pH 4 exhibit linear amperometric response for thiocyanate concentration in the range 10 À7 and 10 À3 M. Theoretical calculations show that electrocatalytic activity (as log i at constant E) plotted versus the energy of the LUMO of the Co complex also gives a volcano correlation.

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Tuning the Formal Potential of Metallomacrocyclics for Maximum Catalytic Activity For the Oxidation of Thiols and Hydrazine

Cited by 7 publications

References 49 publications

Theoretical Study of Sensitizer Candidates for Dye-Sensitized Solar Cells: Peripheral Substituted Dizinc Pyrazinoporphyrazine–Phthalocyanine Complexes

Theoretical Study of Sensitizer Candidates for Dye-Sensitized Solar Cells: Peripheral Substituted Dizinc Pyrazinoporphyrazine–Phthalocyanine Complexes

Hydrazine Oxidation Electrocatalysis

Optimizing the Electrocatalytic Activity of Surface Confined Co Macrocyclics for the Electrooxidation of Thiocyanate at pH 4

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