Metallocorroles as Photocatalysts for Driving Endergonic Reactions, Exemplified by Bromide to Bromine Conversion

Mahammed, Atif; Gross, Zeev

doi:10.1002/ange.201503064

Cited by 16 publications

(6 citation statements)

References 46 publications

(23 reference statements)

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“…This was inspired by our recent invention, in which we have tested several metallocorroles (including the fully brominated phosphorus corrole) and deduced that Ga-Br 8 is most efficient because its photoexcited state has the most oxidizing power. 85 Using HBr, we first tested the efficacy of 5 and P-Br 5 (Figure S15) relative to Ga-Br 8 , based on the conclusions reached from work with the latter: the direct correlation between high oxidation potentials and efficacy. The first evaluation assay was based on quantification of bromine formed in catalyst-containing CH 3 CN/HBr solutions, relying on the UV−vis absorbance of the Br 3 − species (ε 259 nm = 55000 L mol −1 cm −1 ).…”

Section: ■ Results and Discussionmentioning

confidence: 92%

Maximizing Property Tuning of Phosphorus Corrole Photocatalysts through a Trifluoromethylation Approach

et al. 2019

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An eight-member series of CF3-substituted difluorophosphorus corroles was prepared for establishing a structure–activity profile of these high-potential photosensitizers. It consisted of preparing all four possible isomers of the monosubstituted corrole and complexes with 2-, 3-, 4-, and 5-CF3 groups on the macrocycle’s periphery. The synthetic pathway to these CF3-substituted derivatives, beginning with (tpfc)PF 2 , involves two different initial routes: (i) direct electrophilic CF3 incorporation using FSO2CF2CO2Me and copper iodide, or (ii) bromination to achieve the 2,3,8,17,18-pentabrominated compound using excess bromine in methanol. Crystallographic investigations revealed that distortion of the original planar macrocycle is evident even in the monosubstituted case and that it becomes truly severe for the penta-CF3-substituted derivative 5. There is a shift in redox potentials of about 193 mV per -CF3 group, which decreases to only 120 mV for the fifth one in 5. Differences in the electronic spectra suggest that the Gouterman four orbital model decreases in relevance upon gradual -CF3 substitution, a conclusion that was corroborated by DFT calculations. The very significant energy lowering of the frontier orbitals suggested that photoexcitation should lead to a highly oxidizing photocatalyst. This hypothesis was proven true by finding that the most synthetically accessible CF3-substituted derivative is an excellent catalyst for the photoinduced conversion of bromide to bromine (phenol, toluene, and benzene assay).

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Section: ■ Results and Discussionmentioning

confidence: 92%

Maximizing Property Tuning of Phosphorus Corrole Photocatalysts through a Trifluoromethylation Approach

et al. 2019

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“…Gross and co-workers recently reported the photocatalytic oxidation of bromide to bromine with metallocorroles 169−172 (Figure 77). 299 Complex 172 was not competent for the photooxidation of bromide because it was demetalated by hydrobromic acid. The λ max (Soret band) values of 171, 169, and 170 are 428, 437, and 438 nm, respectively.…”

Section: Simple Oer Catalystsmentioning

confidence: 99%

Energy-Related Small Molecule Activation Reactions: Oxygen Reduction and Hydrogen and Oxygen Evolution Reactions Catalyzed by Porphyrin- and Corrole-Based Systems

2016

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Globally increasing energy demands and environmental concerns related to the use of fossil fuels have stimulated extensive research to identify new energy systems and economies that are sustainable, clean, low cost, and environmentally benign. Hydrogen generation from solar-driven water splitting is a promising strategy to store solar energy in chemical bonds. The subsequent combustion of hydrogen in fuel cells produces electric energy, and the only exhaust is water. These two reactions compose an ideal process to provide clean and sustainable energy. In such a process, a hydrogen evolution reaction (HER), an oxygen evolution reaction (OER) during water splitting, and an oxygen reduction reaction (ORR) as a fuel cell cathodic reaction are key steps that affect the efficiency of the overall energy conversion. Catalysts play key roles in this process by improving the kinetics of these reactions. Porphyrin-based and corrole-based systems are versatile and can efficiently catalyze the ORR, OER, and HER. Because of the significance of energy-related small molecule activation, this review covers recent progress in hydrogen evolution, oxygen evolution, and oxygen reduction reactions catalyzed by porphyrins and corroles.

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“…Amphiphilic gallium corroles also exhibit strong activity against a number of cancer cell lines as well as in vivo against tumors in mouse models. Elsewhere, in a study of potential relevance to solar energy conversion, β-octabrominated complexes M[Br 8 TPFPC](py) 2 have been shown to act as highly stable photocatalysts for aerobic oxidation of bromide to elemental bromine in the presence of trifluoroacetc acid . These applications have been reviewed elsewhere in this issue.…”

Section: Free-base and Main-group Corrolesmentioning

confidence: 99%

Electronic Structure of Corrole Derivatives: Insights from Molecular Structures, Spectroscopy, Electrochemistry, and Quantum Chemical Calculations

2017

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Presented herein is a comprehensive account of the electronic structure of corrole derivatives. Our knowledge in this area derives from a broad range of methods, including UV-vis-NIR absorption and MCD spectroscopies, single-crystal X-ray structure determination, vibrational spectroscopy, NMR and EPR spectroscopies, electrochemistry, X-ray absorption spectroscopy, and quantum chemical calculations, the latter including both density functional theory and ab initio multiconfigurational methods. The review is organized according to the Periodic Table, describing free-base and main-group element corrole derivatives, then transition-metal corroles, and finally f-block element corroles. Like porphyrins, corrole derivatives with a redox-inactive coordinated atom follow the Gouterman four-orbital model. A key difference from porphyrins is the much wider prevalence of noninnocent electronic structures as well as full-fledged corrole radicals among corrole derivatives. The most common orbital pathways mediating ligand noninnocence in transition-metal corroles are the metal(d)-corrole("a") interaction (most commonly observed in Mn and Fe corroles) and the metal(d)-corrole(a) interaction in coinage metal corroles. Less commonly encountered is the metal(d)-corrole("a") interaction, a unique feature of formal d metallocorroles. Corrole derivatives exhibit a rich array of optical properties, including substituent-sensitive Soret maxima indicative of ligand noninnocence, strong fluorescence in the case of lighter main-group element complexes, and room-temperature near-IR phosphorescence in the case of several 5d metal complexes. The review concludes with an attempt at identifying gaps in our current knowledge and potential future directions of electronic-structural research on corrole derivatives.

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Metallocorroles as Photocatalysts for Driving Endergonic Reactions, Exemplified by Bromide to Bromine Conversion

Cited by 16 publications

References 46 publications

Maximizing Property Tuning of Phosphorus Corrole Photocatalysts through a Trifluoromethylation Approach

Maximizing Property Tuning of Phosphorus Corrole Photocatalysts through a Trifluoromethylation Approach

Energy-Related Small Molecule Activation Reactions: Oxygen Reduction and Hydrogen and Oxygen Evolution Reactions Catalyzed by Porphyrin- and Corrole-Based Systems

Electronic Structure of Corrole Derivatives: Insights from Molecular Structures, Spectroscopy, Electrochemistry, and Quantum Chemical Calculations

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