Catalytic electroreduction of molecular oxygen using iron or cobalt 4,4',4",4'"-tetracarboxyphthalocyanine
01 Jan 1985-The Journal of Physical Chemistry (American Chemical Society)-Vol. 89, Iss: 7, pp 1167-1170
TL;DR: In this paper, the tetracarboxyphtalocyanines de Fe et de Co. were used for the electroreduction of loxygene dans une solution aqueuse contenant des tetrasetracarboxesyphalocyanine de Fe and Co.
Abstract: Etudes de l'electroreduction de l'oxygene dans une solution aqueuse contenant des tetracarboxyphtalocyanines de Fe et de Co
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TL;DR: The thermochemistry of oxygen reduction and the factors influencing ORR efficiency are described to contextualize the discussion of catalytic studies that follows, and reports of ORR catalysis are presented in terms of their mechanism.
Abstract: The oxygen reduction reaction (ORR) is a key component of biological processes and energy technologies This Review provides a comprehensive report of soluble molecular catalysts and electrocatalysts for the ORR The precise synthetic control and relative ease of mechanistic study for homogeneous molecular catalysts, as compared to heterogeneous materials or surface-adsorbed species, enables a detailed understanding of the individual steps of ORR catalysis Thus, the Review places particular emphasis on ORR mechanism and thermodynamics First, the thermochemistry of oxygen reduction and the factors influencing ORR efficiency are described to contextualize the discussion of catalytic studies that follows Reports of ORR catalysis are presented in terms of their mechanism, with separate sections for catalysis proceeding via initial outer- and inner-sphere electron transfer to O2 The rates and selectivities (for production of H2O2 vs H2O) of these catalysts are provided, along with suggested methods for acc
384 citations
TL;DR: The effects of the increase in the size of the ring system were clearly derived and the HOMO destabilization with molecular size differs depending on the central metal, so metals producing smaller destabilization effects can allow larger macrocycles.
Abstract: Tetraazaporphyrins (TAPs), phthalocyanines (Pcs), naphthalocyanines (Ncs), and anthracocyanines (Acs) with four tert-butyl groups attached at similar positions have been synthesized, and their electronic absorption, magnetic circular dichroism (MCD), IR, and voltammetric properties were studied and interpreted with the help of quantum-mechanical calculations. Through the preparation of a series of compounds with the same number of the same substituent, the effects of the increase in the size of the ring system were clearly derived. The main results may be summarized as follows. 1) The Q band shifts to longer wavelength and its intensity increases, but with decreasing degree of change with increasing molecular size. If the size of the effect of benzene directly fused to the TAP skeleton is set at unity, the effects of the second and third benzene units are roughly 0.8 and 0.5, respectively. 2) The splitting of the Q bands in metal-free compounds decreases with increasing molecular size, so that the Q bands of H2Nc and H2Ac appear as single bands. 3) The magnitude of the orbital angular momentum of the excited state of the ligand decreases with increasing molecular size. 4) Interestingly, the ring current, as judged from the positions of pyrrole proton signals in the 1H NMR spectrum, appears to decrease with increasing molecular size. 5) The first reduction potential becomes less negative, but only slightly, whereas the first oxidation potential shows a marked shift to less positive values with increasing molecular size, indicating that the HOMO destabilizes significantly as the molecule becomes larger. 6) In 5), the extent of the HOMO destabilization with molecular size differs depending on the central metal, so metals producing smaller destabilization effects can allow larger macrocycles. Of the metals studied, the most effective is cobalt, and the practical size limit is represented by the Acs. 7) The IR spectra become simpler the larger the molecule, and the main bands were assigned by DFT calculations. 8) The trend in experimentally determined redox potentials and electronic absorption and MCD spectra were reasonably reproduced by MO calculations using the ZINDO/S Hamiltonian. 9) EPR data for several metallocomplexes are also reported.
150 citations
TL;DR: In this article, a synthese sur l'utilisation d'electrocatalyseurs comme les porphyrines metalliques, les phtalocyanines and d'autres macrocycliques lors de la reduction de l'oxygene moleculaire is presented.
Abstract: Article de synthese sur l'utilisation d'electrocatalyseurs comme les porphyrines metalliques, les phtalocyanines et d'autres macrocycliques lors de la reduction de l'oxygene moleculaire
143 citations
TL;DR: In this article, the tetra-aminophthalocyane to, cobalt(II) species adsorbed onto graphite electrodes are active in electrocatalytic oxygen reduction.
Abstract: The monomeric and polymeric tetra-aminophthalocyane to, cobalt(II) species adsorbed onto graphite electrodes are active in electrocatalytic oxygen reduction. While the monomeric species is unstable, the polymerized species is an effective and stable reduction catalyst over a wide pH range. Both the two-electron reduction of oxygen to hydrogen peroxide and the four-electron reduction of oxygen to water are characterized by cyclic voltammetry, rotating disc and rotating ring-disc studies with appropriate theoretical analysis. Some mechanistic information is obtained. This is the first cobalt phthalocyanine species to provide a four-electron reduction pathway which exists over a wide pH range and is stable. The stability is associated with the polymerization since the monomeric species is not stable.
107 citations
TL;DR: In this article, the state of the art in sustainable metal catalysis is summarized, that is, catalysis based upon inexpensive biorelevant metals such as Ca, Mg, V, Mo, Mn, Fe, Co, Ni, Cu, Zn, B, Si, and Se.
Abstract: A growing world population and increasing energy demands are without a doubt the most important challenges for mankind within this century. Catalysis is a key technology in various fields of chemistry and offers the potential to increase the material output of chemical synthesis without an unreasonable increase in the energy necessary for the production of new materials. Hence, the various disciplines of catalysis are “sustainable” by definition. However, for a wide range of catalytic transformations to take the necessary next step from academic research to industrial application, the catalytic processes do not only have to be sustainable with regard to the substrate-to-product conversions, but they also have to be sustainable with regard to parameters such as solvent, energy source, and the nature of the catalyst. Currently, the vast majority of transition-metal-catalyzed homogenous reactions are based upon late and expensive transition-metal complexes. In the present review we summarize the current state of the art in sustainable metal catalysis, that is, catalysis based upon inexpensive biorelevant metals such as Ca, Mg, V, Mo, Mn, Fe, Co, Ni, Cu, Zn, B, Si, and Se. These metals are part of nature’s catalytic toolbox and have experienced a tremendous comeback in metal catalysis within the past 10 years.
94 citations