38673-65-3Relevant articles and documents
Photoinduced Electron Transfer Reactions of Water Soluble Porphyrins in Zeolite Environment
Velappan, Kandavelu,Rajalingam, Renganathan,Venkattappan, Anbazhagan
, p. 1575 - 1585 (2021)
Excited state interactions of zeolite adsorbed porphyrins have been investigated by steady state luminescence quenching technique with certain antioxidants such as reduced glutathione, ascorbic acid and L-cysteine. The zeolite supported porphyrins, meso-tetra (N-methyl-4-pyridyl) porphyrin (H2TMPyP4+) and zinc tetra(N-methyl-4-pyridyl) porphyrin (ZnTMPyP4+) were prepared and characterized by various techniques such as Diffuse Reflectance Spectra (DRS), Scanning Electron Microscope (SEM), powder X-Ray Diffraction (XRD) and BET surface area. The interaction of zeolites with porphyrins are shown to increase the lifetime of the singlet excited state of porphyrins and decays are biphasic in nature. The splitting of the emission band of porphyrins occurs in 1:1 glycerol: water solution due to the changes in the dielectric of the solvation sphere associated with porphyrin. The Stern-Volmer plots of I0/I vs quencher concentration [Q] were linear in the whole range of [Q] used. These studies revealed the effective quenching for zinc porphyrin compared to free base porphyrin. The effect of quenchers and zeolite acidity has also been studied and the quenching rate constant (kq) is found in the order of 109?M?1?s?1. The quenching reaction obeys Rehm-Weller Equation and is shown to be due to thermodynamically favoured electron transfer from quenchers to the excited singlet state of porphyrins (reductive quenching).
Photophysical and Redox Properties of Water-Soluble Porphyrins in Aqueous Media
Kalyanasundaram, K.,Neumann-Spallart, M.
, p. 5163 - 5169 (1982)
Various photophysical (spectra, lifetimes, and quantum yields for fluorescence, phosphorescence, T-T absorption spectra, and quantum yields for triplet formation) and redox (potentials for one-and two-electron oxidation and reduction) properties of several water-soluble porphyrins (H2TPPS, H2TMPyP, ZnTPPS, ZnTMPyP, ZnTPPC, PdTPPS, PdTMPyP, and PdTPPC where TPPS=tetrakis(sulfonatophenyl)porphyrin, TMPyP=tetrakis(N-methylpyridyl)porphyrin, and TPPC=tetrakis(carboxyphenyl)porphyrin in aqueous solution have been studied.The tetrakis(N-methylpyridyl)porphyrins are characterized by reduced fluorescence yields, higher triplet yields, and long lifetimes with intense T-T absorptions extending up to 1200 nm.The redox potentials of these cationic porphyrins are also shifted to more positive potentials by 350-400 mV with respect to those of anionic TPPS systems.
"ship in a bottle" Porph@MOMs as highly efficient catalysts for selective controllable oxidation and insights into different mechanisms in heterogeneous and homogeneous environments
Saghian,Dehghanpour,Sharbatdaran
supporting information, p. 12872 - 12881 (2018/08/01)
In the present work, three "ship in a bottle" Porph@MOMs are reported as biomimetic oxidation catalysts for different reactions. These frameworks are constructed from trimesic acid and metal ions (M = Fe, Co and Mn) in which tetra(N-methyl-4-pyridyl)porphyrin (MTMPyP) is encapsulated within the cavities. Additionally, the catalytic activities of the corresponding homogeneous compounds, FeTMPyP, CoTMPyP and MnTMPyP, and the frameworks without porphyrins within the cavities were investigated in the foregoing oxidation reactions. The prepared 3D porous structures have the ability to control selectivity toward the desired product. Furthermore, they are capable of acting as effective peroxidase mimics, which successfully catalyze the oxidation of diverse olefins as well as hydrocarbons using TBHP as an oxidant. The heterogeneous catalysts significantly enhance conversion in contrast to their corresponding homogeneous systems. Remarkably, an insight into the catalyst behavior was gained from the proposed mechanism based on the reversal of selectivity. Investigation of the stability and reusability of the catalysts revealed the heterogeneity character of the catalyst with no desorption during the course of oxidation reactions. The high yields, clean reactions, high thermal stability and reusability of the catalysts make them good candidates for heterogeneous catalysts in various oxidation reactions.
Ionic interactions of anionic thiacalix[4]arene with cationic porphyrins
Garg, Bhaskar,Bisht, Tanuja,Chauhan, Shive Murat Singh
experimental part, p. 161 - 178 (2010/09/11)
A facile synthesis of 25,26,27,28-tetrakis(alkyloxy)-2,8,14,20- tetrathiacalix[4]arene-5,11,17,23-tetrasulfonate via ipso substitution of p-tert-butylthiacalix[4]arene tetraalkyl ether with sulfuric acid is described. Ionic interaction of anionic thiacalix[4]arene and cationic porphyrins were quantitatively studied by UV-vis, fluorescence, 1H NMR and ESI-MS spectrometry. Binding constants were in the range of 10 8 M -1. Binding with axial ligands was investigated and formation of ternary complexes was recognized with pyridine, 4-methylpyridine and Nmethylimidazole. The factors affecting the interaction process including pH, solvents and salts were also examined in detail. The results indicated that the neutral medium (pH = 7) is most favorable for electrostatic interactions. ARKAT USA, Inc.