TL;DR: 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.
Abstract: 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. Becau...
TL;DR: The pH dependence of the water splitting reaction suggests a proton-coupled electron transfer (PCET) catalytic mechanism and the turnover frequencies for the 4e(-)/4H(+) process at the single cobalt center of the hangman platform approach 1 s(-1).
Abstract: Cobalt hangman corrole, bearing β-octafluoro and meso-pentafluorophenyl substituents, is an active water splitting catalyst. When immobilized in Nafion films, the turnover frequencies for the 4e–/4H+ process at the single cobalt center of the hangman platform approach 1 s–1. The pH dependence of the water splitting reaction suggests a proton-coupled electron transfer (PCET) catalytic mechanism.
TL;DR: The solvent-free, catalyst-free condensation of pyrrole and aldehydes provides an extremely facile synthetic pathway to novel corroles, including an ionic, water-soluble corrole.
Abstract: The solvent-free, catalyst-free condensation of pyrrole and aldehydes provides an extremely facile synthetic pathway to novel corroles [Eq. (1); Ar=C6F5, 2,6-F2C6H3, 2,6-Cl2C6H3]. The product containing pentafluorophenyl groups is an excellent precursor of other derivatives, including an ionic, water-soluble corrole.
TL;DR: This survey reveals many examples where corroles were used as the key components in catalysis, sensing of gaseous molecules and medicine-oriented research, and the focus in all these cases was on the special features of corroles: stabilization of high valent transition metal ions, unique photophysical properties, large NH acidity, facile synthetic manipulation and distinct catalytic properties.
TL;DR: A comprehensive account of the electronic structure of corrole derivatives with a redox-inactive coordinated atom follow the Gouterman four-orbital model, which exhibits 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
Abstract: 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•2– radicals among corrole derivatives. The most common orbital pathways mediating ...