119273-07-3Relevant academic research and scientific papers
One- and Two-Electron Reduction of Metalloporphyrins. Radiation Chemical, Photochemical, and Electrochemical Studies. Kinetics of the Decay of ?-Radical Anions
Richoux, M. C.,Neta, P.,Harriman, Anthony,Baral, S.,Hambright, P.
, p. 2462 - 2468 (1986)
One- and two-electron reduction products of several metalloporphyrins have been studied by steady-state and pulse radiolysis in aqueous and methanolic slutions and by photochemistry and electrochemistry in aqueous solutions.This study concentrates on the TMPyP (tetrakis(N-methyl-4-pyridyl)porphyrin) complexes of GaIII, GeIV, and InIII, and the TPyP (tetra(3-pyridyl)porphyrin) complex of SbV, and compares them with the previously studied complexes of ZnII, AlIII, and SnIV.All these porphyrins undergo one-electron reduction on the ligand to form ?-radical anions.The rates of formation and decay of these species have been studied under various conditions.The lifetimes of these radicals were found to vary greatly; those of SbV and SnIV are completely stable while some others decay in the millisecond range.The stability decreases in the order SbV, SnIV, InIII, GeIV, GaIII, AlIII, ZnII, which was found to correspond to the order of the porphyrin ring reduction potentials determined under similar conditions.Increased lifetime of the radical upon increase in electronegativity of the metal was found to be due to inhibition of porphyrin ring protonation, which is a necessary step in the formation of final products.The final two-electron reduction products are mainly phlorin anions.The same products were observed upon photochemical reduction.The potentials for the first and second one-electron reduction of the porphyrins were determined by cyclic voltammetry.The separation between the first and second wave gives an indication of the stability of the ?-radical anion.
Electron-Transfer Reactions between C60 and Radical Ions of Metalloporphyrins and Arenes
Guldi, Dirk M.,Neta, Pedatsur,Asmus, Klaus-Dieter
, p. 4617 - 4621 (2007/10/02)
Electron-trnsfer reactions with C60 leading to the singly reduced and oxidized radical ions, C60.- and C60.+, have been studied by pulse radiolysis. ?-Radical anions of several metalloporphyrins (tetraphenyl- and tetrapyridylporphyri
Photoreactivity of σ-bonded metalloporphyrins. 1. Formation of zwitterionic indium and gallium porphyrin complexes in tetrahydrofuran
Kadish,Maiya,Xu
, p. 2518 - 2523 (2008/10/08)
Continuous irradiation and laser-flash photolysis experiments were carried out in THF on σ-bonded indium and gallium porphyrins of the type (P)M(R), where P is the dianion of tetraphenylporphyrin (TPP) or octaethylporphyrin (OEP), M is In or Ga, and R is CH3, C2H5, C4H9, CH(CH3)2, C(CH3)3, CH=CHC6H5, or C≡CC6H5. Steady-state photolysis of (P)M(R), where R = CH3, C2H5, C4H9, CH(CH3)2, or C(CH3)3, leads to photodissociation of the metal-carbon bond. In contrast, indium and gallium porphyrins with σ-bonded CH=CHC6H5 or C≡CC6H5 groups do not undergo this photodissociation reaction. Laser photolysis studies were carried out both in the presence and in the absence of ferrocene and indicate that the photoreaction occurs via a triplet state originating from the porphyrin macrocycle. The resulting ESR spectra obtained after photolysis of (TPP)In(C2H5) in THF are compared with ESR spectra obtained after electrochemical reduction of (TPP)InCl. On the basis of these results, a photochemical generation of zwitterionic metalloporphyrin radicals of the type (P)-In+ is demonstrated to occur in THF. Similarly, the (P)Ga(R) complexes also form a zwitterionic photoproduct upon irradiation as evidenced by ESR and UV-visible spectra. The photoreactivity of (P)In(R) and (P)Ga(R) is discussed with respect to the porphyrin macrocycle, the σ-bonded R group, and the solvent polarity.
