- Photoinduced Electron Transfer Reactions of Water Soluble Porphyrins in Zeolite Environment
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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).
- Velappan, Kandavelu,Rajalingam, Renganathan,Venkattappan, Anbazhagan
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- Electron Transfer between Cytochrome c and Porphyrins
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The electron transfer between cytochrome c and several water-soluble porphyrins (ZnTPPS, ZnTMPyP, ZnTPPC, H2TPPS, and H2TMPyP where TPPS is tetrakis(sulfonatophenyl)porphyrin, TMPyP is tetrakis(N-methylpyridyl)porphyrin, and TPPC is tetrakis(carboxyphenyl)porphyrin has been studied by the method of photoexcitation.For each porphyrin, two rates corresponding to electron transfer from porphyrin triplet to ferricytochrome c and from ferrocytochrome c to porphyrin cation radical are determined.The second-order rate constant increases from 3.5E8 to 11E8 M1- s1- (25 deg C, 0.5M ionic strength, pH 7.0) as the driving force ΔE for the reaction increases from 0.54 to 1.06 V.A reorganization energy of 1.0 eV was deduced for the above electron-transfer reactions, when the rates (at infinite ionic strength) are analyzed according to the theories of Marcus and Hopfield.
- Cho, K. C.,Che, C. M.,Ng, K. M.,Choy, C. L.
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- Photophysical and Redox Properties of Water-Soluble Porphyrins in Aqueous Media
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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.
- Kalyanasundaram, K.,Neumann-Spallart, M.
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- Effect of structural variation on tumor targeting efficacy of cationically charged porphyrin derivatives: Comparative in-vitro and in-vivo evaluation for possible potential in PET and PDT
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Tetracationic (TMPyP) and tricationic porphyrin (TriMPyCOOHP) derivatives were synthesized, characterized and investigated for binding with DNA by Isothermal Titration Calorimetry as well as by UV–Vis spectroscopy in order to study the effect of structural variation on tumor targeting efficacy of cationically charged porphyrin derivatives. Fluorescence cell imaging studies performed in cancer cell lines corroborated the findings of aforementioned studies. Photocytotoxicity experiments in A549 cell lines revealed relatively higher light dependent cytotoxic effects exerted by TMPyP compared to TriMPyCOOHP. In-vivo experiments in tumor bearing animal model revealed relatively longer retention of 68Ga-TMPyP in tumorous lesion compared to that of 68Ga-TriMPyCOOHP. The study reveals that removal of one of the positive charges of the tetracationic porphyrin derivatives significantly reduces their DNA binding ability and cytotoxicity as well as brings changes in the pharmacokinetic pattern and tumor retention in small animal model.
- Guleria, Mohini,Suman, Shishu K.,Mitra, Jyotsna B.,Shelar, Sandeep B.,Amirdhanayagam, Jeyachitra,Sarma, Haladhar D.,Dash, Ashutosh,Das, Tapas
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- "ship in a bottle" Porph@MOMs as highly efficient catalysts for selective controllable oxidation and insights into different mechanisms in heterogeneous and homogeneous environments
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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.
- Saghian,Dehghanpour,Sharbatdaran
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supporting information
p. 12872 - 12881
(2018/08/01)
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- Cationic porphyrin@SPION nanospheres as multifunctional anticancer therapeutics: Magnetic targeting, photodynamic potential and bio-safety research
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The synthesis and characterization of carboxyl-functionalized superparamagnetic iron oxide nanoparticles (SPION)-attached cationic porphyrins with different positive charges (porphyrin@SPION) are described as pH-sensitive, multifunctional photosensitization. These nanospheres exhibit excellent targeted cell accumulation under external magnetic field and outstanding cell photocytotoxicity in weak acidic solution, which is the pH for most tumors. The dicationic porphyrin@SPION has the smartest pH-responding release and lowest half-maximal inhibitory concentration (IC50) values after visible light irradiation against HeLa cells. Moreover, the delivery safety of these porphyrin@SPION nanospheres was considered by investigating their behaviors in human plasma during the delivery process. The results elucidate that these nanospheres have no significant deleterious influence on the frame conformation of protein in their delivery process and thus are relatively safe in the drug delivery process. Our study demonstrates that the combination of targeted magnetic-loading drug design methodology with the PDT potential of cationic porphyrins may be a very useful strategy to develop novel tumor-oriented multifunctional anticancer therapeutics.
- Zhao, Ping,Liu, Min-Chao,Madanayake, Thushara W.,Reena, Chawla,Zheng, Min,Cheng, Zhen-Feng,Huang, Yu-Min,Wang, Xia-Hong
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p. 103137 - 103148
(2016/11/13)
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- Ionic interactions of anionic thiacalix[4]arene with cationic porphyrins
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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.
- Garg, Bhaskar,Bisht, Tanuja,Chauhan, Shive Murat Singh
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experimental part
p. 161 - 178
(2010/09/11)
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