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Porphyrin Complex (porphyrin + complex)
Selected AbstractsUltrafast Vibronic Processes in a Ru,Porphyrin ComplexEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 31 2008Izumi Iwakura Abstract The excited-state dynamics of RuII(TPP)(CO)(acetone) (TPP = tetraphenylporphyrin) was investigated by using a sub-5-fs pulse. In previous studies, the fluorescence lifetime of RuII(TPP)(CO) could not be resolved and was reported to be <1 ps. Analysis of the six-coordinate complexes of RuII(TPP)(CO)(acetone) showed that 1Qx(,,,*) had a lifetime of 140,±,20 fs and the lifetime of 3(d,,*) was 560,±,150 fs. Stimulated emission due to a spin-forbidden transition from 3(,,,*) to the ground state was observed for the first time.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] General and Selective Olefination of Aldehydes and Ketones Catalyzed by a Cobalt(II) Porphyrin Complex.CHEMINFORM, Issue 13 2004Ming-Yung Lee Abstract For Abstract see ChemInform Abstract in Full Text. [source] ChemInform Abstract: Regioselective Oxidations of Equilenin Derivatives Catalyzed by a Rhodium(III) Porphyrin Complex , Contrast with the Manganese(III) Porphyrin.CHEMINFORM, Issue 3 2001Jerry Yang Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] A Bevel-Gear-Shaped Rotor Bearing a Double-Decker Porphyrin ComplexCHEMISTRY - A EUROPEAN JOURNAL, Issue 28 2010Soichiro Ogi Supramolecular rotor: The interlocking of two porphyrin-based molecular rotors into a bevel-gear-shaped structure is demonstrated (see figure). The mechanical interactions between the teeth of the two porphyrin rotors enabled them to mesh and rotate with almost identical activation energies. Switching the rotational activities of one rotor by using chemical stimulation induced a change in the cooperative rotational motions of both rotors. [source] Oxidation of ,4 - and ,5 -Steroids with Hydrogen Peroxide Catalyzed by Porphyrin Complexes of MnIII and FeIIIEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 23 2004Susana L. H. Rebelo Abstract In this paper we describe a new environmentally friendly method to promote the stereoselective epoxidation of ,4 - and ,5 -steroids. Metalloporphyrins efficiently catalyze the epoxidation reactions of 17,-acetoxy-4-androstene (1), 4-cholestene (2) and 3,-acetoxy-5-cholestene (3) in the presence of H2O2 as oxygen donor. Modeling the molecular structure of the porphyrin as well as the central metal allows the control of the preferential formation of ,- or ,-epoxides. Porphyrins with bulky, electron-withdrawing groups in the ortho positions of the meso phenyls and with MnIII as the central metal ion, such as [Mn(TDCPP)Cl], gave preferentially the ,-epoxide of ,4 - and ,5 -steroids. [Fe(TPFPP)Cl] catalyzes preferentially the ,-epoxidation of ,4 -steroids and also increases the stereoselectivity for the ,-epoxide in ,5 -steroids, similar to the results obtained with m -CPBA (m -chloroperbenzoic acid) as oxidant. The substrate structure strongly influences the chemoselectivity of the reactions. The X-ray structures of two main products were determined, and two-dimensional NMR techniques allowed the full assignment of 1H and 13C NMR resonances as well as the stereochemistry of these products. A mechanistic proposal involving oxo species for the ,-approach and peroxy species for the ,-approach is proposed. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source] Thermally Activated Delayed Fluorescence from Sn4+,Porphyrin Complexes and Their Application to Organic Light Emitting Diodes , A Novel Mechanism for ElectroluminescenceADVANCED MATERIALS, Issue 47 2009Ayataka Endo Electroluminescence based on TADF, that is, thermally activated delayed fluorescence, is demonstrated in Sn4+,porphyrin complexes. On excitation by a short electrical pulse, prompt and delayed electroluminescence components were clearly observed. The delayed component was composed of both TADF and phosphorescence (see figure), and the TADF component significantly increased with increasing temperature. [source] Diboryl and Diboranyl Porphyrin Complexes: Synthesis, Structural Motifs, and Redox Chemistry: Diborenyl Porphyrin or Diboranyl Isophlorin?CHEMISTRY - A EUROPEAN JOURNAL, Issue 21 2007Andre Weiss Dr. Abstract The syntheses of diboryl porphyrin complexes [(BX2)2(ttp)] (ttp: dianion of tetra- p -tolylporphyrin) and the BB single-bond diboranyl complexes [(BX)2(ttp)] (X=F, Cl, Br, I) are given. The former are prepared from the reactions of BX3 (X=F, Cl) with [Li2(ttp)] and the latter from B2Cl4 (X=Cl), the reaction of SbF3 with [(BCl)2(ttp)] (for X=F), and, in the cases of X=Br or I, in a remarkable reductive coupling reaction resulting directly from the reaction of BBr3 or BI3 with [Li2(ttp)]. Density functional theory (DFT) calculations on the thermochemical parameters for the reductive coupling reactions (and those calculated for related dipyrromethene complexes) indicate that a combination of the reducing ability of bromide and iodide ions combined with the constrained environment of the porphyrin ligand contribute to the driving force. The reductive coupling is also observed in the reaction of [(BCl2)2(ttp)] with nBuLi to give [(BnBu)2(ttp)], which was characterised crystallographically. The reaction of [(BCl)2(ttp)] with catechol gives a boron catecholato porphyrin complex, [B2(O2C6H4)(ttp)]. Chloride abstraction from [(BCl)2(ttp)] gives the planar dication [B2(ttp)]2+, whereas chemical reduction of [(BCl)2(ttp)] by using magnesium anthracenide gives a neutral complex, [B2(ttp)], in which the TTP ligand has been reduced by two electrons to give an unusual example of an isophlorin complex. The cationic and neutral complexes [B2(ttp)]2+ and [B2(ttp)] were characterised through a combination of spectroscopic data that is supported by DFT calculations on the porphine analogues. [source] Metal-complex formation and DNA interaction of 5, 10,15,20-tetrakis(1-methyl-4-pyridiyl)-porphine: Study of the mechanistic aspectsINTERNATIONAL JOURNAL OF CHEMICAL KINETICS, Issue 2 2010Sabriye Aydinoglu The macrocyclic porphyrin 5,10,15,20-tetrakis(1-methyl-4-pyridiyl)-porphine is studied in its ability to coordinate Cu(II) even at very low pH values and to interact, as a copper complex, with calf-thymus (CT-DNA). The kinetics and equilibria for metal-ligand complexes formation are spectrophotometrically studied, particularly focussing on the mechanistic information provided by the kinetic approach. The rate constants of complex formation is much lower than that of water exchange at Cu(II); this behavior is ascribed to an equilibrium between two porphyrin populations, only one of them being reactive. Concerning the interaction of the copper,porphyrin complex (D) with CT-DNA, it has been found that the complex binds to G,C base pairs by intercalation while forms external complex with the A,T base pairs. The kinetic results agree with a reaction mechanism that takes into account the slow shuffling from an AT-bound form (DAT) to a GC-bound form (DGC) of the copper complex (D), finally leading to a more stable DGC* intercalated form. Kinetic and equilibrium parameters for the copper complex binding to the nucleic acid are obtained, and the binding mechanism is discussed. A mechanism is proposed where D reacts simultaneously with (G,C) and (A,T) base pairs. The resulting bound forms interconvert according to a "shuffling" process, which involves formation of an intermediate (DGC) form. © 2009 Wiley Periodicals, Inc. Int J Chem Kinet 42: 79,89, 2010 [source] Metalloporphyrin/Iodine(III)-Cocatalyzed Oxygenation of Aromatic HydrocarbonsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 9 2010Akira Yoshimura Abstract Hypervalent iodine species have a pronounced catalytic effect on the metalloporphyrin-mediated oxygenations of aromatic hydrocarbons. In particular, the oxidation of anthracene to anthraquinone with Oxone readily occurs at room temperature in aqueous acetonitrile in the presence of 5,20,mol% of iodobenzene and 5,mol% of a water-soluble iron(III)-porphyrin complex. 2- tert -Butylanthracene and phenanthrene also can be oxygenated under similar conditions in the presence of 50,mol% of iodobenzene. The oxidation of styrene in the presence of 20,mol% of iodobenzene leads to a mixture of products of epoxidation and cleavage of the double bond. Partially hydrogenated aromatic hydrocarbons (e.g., 9,10-dihydroanthracene, 1,2,3,4-tetrahydronaphthalene, and 2,3-dihydro-1H -indene) afford under these conditions products of oxidation at the benzylic position in moderate yields. The proposed mechanism for these catalytic oxidations includes two catalytic redox cycles: 1) initial oxidation of iodobenzene with Oxone producing the hydroxy(phenyl)iodonium ion and hydrated iodosylbenzene, and 2) the oxidation of iron(III)-porphyrin to the oxoiron(IV)-porphyrin cation-radical complex by the intermediate iodine(III) species. The oxoiron(IV)-porphyrin cation-radical complex acts as the actual oxygenating agent toward aromatic hydrocarbons. [source] Synthesis of imidazole and imidazolium porphyrinsJOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 4 2006Virginia Seng A new porphyrin compound, where an imidazole group was attached through the 1-position nitrogen to a phenyl ring located on the porphyrin periphery has been synthesized and characterized. The second nitrogen on the imidazole is available for further chemistry as demonstrated by the attachment of bromopentane forming the imidazolium porphyrin complex. This is the first example of an imidazolium group covalently attached to the porphyrin periphery in which the porphyrin is attached through the nitrogen on the imidazole ring rather than a carbon atom. [source] Improvement of hyperglycaemia and metabolic syndromes in type 2 diabetic KKAy mice by oral treatment with [meso-tetrakis(4-sulfonatophenyl) porphyrinato]oxovanadium(IV)(4-) complexJOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 3 2007Tapan Kumar Saha Recently, we reported that [meso-tetrakis(4-sulfonatophenyl)porphyrinato]oxovanadium(IV)(4-), VO(tpps), shows in-vitro insulin-mimetic and in-vivo anti-diabetic activity in streptozotocin (STZ)-induced type 1 diabetic mice. This result prompted us to examine its ability in type 2 diabetic model KKAy mice with insulin resistance. We studied the in-vivo anti-diabetic activity of VO(tpps), compared with that of vanadium(IV) oxide sulfate, VS, as control. Both compounds were orally administered at doses of 5,10 mg (0.1-0.2 mmol) V/kg body weight to the KKAy mice for 28 days. VO(tpps) normalized the hyperglycaemia within 15 days, while VS lowered the blood glucose concentration only by a small degree. In addition, metabolic syndromes characterized by insulin and leptin resistance were significantly improved in VO(tpps)-treated KKAy mice compared with those treated with VS. The improvement in diabetes was validated by oral glucose tolerance test and decrease in HbA1c concentration. Based on these observations, VO(tpps) is proposed to be an orally active oxovanadium(IV)-porphyrin complex for treating not only type 2 diabetes but also metabolic syndromes in animals. [source] Square-grid coordination networks of (5,10,15,20-tetra-4-pyridylporphyrinato)zinc(II) in its clathrate with two guest molecules of 1,2-dichlorobenzene: supramolecular isomerism of the porphyrin self-assemblyACTA CRYSTALLOGRAPHICA SECTION C, Issue 3 2009Rajesh Koner The title compound, (5,10,15,20-tetra-4-pyridylporphyrinato)zinc(II) 1,2-dichlorobenzene disolvate, [Zn(C40H24N8)]·2C6H4Cl2, contains a clathrate-type structure. It is composed of two-dimensional square-grid coordination networks of the self-assembled porphyrin moiety, which are stacked one on top of the other in a parallel manner. The interporphyrin cavities of the overlapping networks combine into channel voids accommodated by the dichlorobenzene solvent. Molecules of the porphyrin complex are located on crystallographic inversion centres. The observed two-dimensional assembly mode of the porphyrin units represents a supramolecular isomer of the unique three-dimensional coordination frameworks of the same porphyrin building block observed earlier. The significance of this study lies in the discovery of an additional supramolecular isomer of the rarely observed structures of metalloporphyrins self-assembled directly into extended coordination polymers without the use of external ligand or metal ion auxiliaries. [source] Diboryl and Diboranyl Porphyrin Complexes: Synthesis, Structural Motifs, and Redox Chemistry: Diborenyl Porphyrin or Diboranyl Isophlorin?CHEMISTRY - A EUROPEAN JOURNAL, Issue 21 2007Andre Weiss Dr. Abstract The syntheses of diboryl porphyrin complexes [(BX2)2(ttp)] (ttp: dianion of tetra- p -tolylporphyrin) and the BB single-bond diboranyl complexes [(BX)2(ttp)] (X=F, Cl, Br, I) are given. The former are prepared from the reactions of BX3 (X=F, Cl) with [Li2(ttp)] and the latter from B2Cl4 (X=Cl), the reaction of SbF3 with [(BCl)2(ttp)] (for X=F), and, in the cases of X=Br or I, in a remarkable reductive coupling reaction resulting directly from the reaction of BBr3 or BI3 with [Li2(ttp)]. Density functional theory (DFT) calculations on the thermochemical parameters for the reductive coupling reactions (and those calculated for related dipyrromethene complexes) indicate that a combination of the reducing ability of bromide and iodide ions combined with the constrained environment of the porphyrin ligand contribute to the driving force. The reductive coupling is also observed in the reaction of [(BCl2)2(ttp)] with nBuLi to give [(BnBu)2(ttp)], which was characterised crystallographically. The reaction of [(BCl)2(ttp)] with catechol gives a boron catecholato porphyrin complex, [B2(O2C6H4)(ttp)]. Chloride abstraction from [(BCl)2(ttp)] gives the planar dication [B2(ttp)]2+, whereas chemical reduction of [(BCl)2(ttp)] by using magnesium anthracenide gives a neutral complex, [B2(ttp)], in which the TTP ligand has been reduced by two electrons to give an unusual example of an isophlorin complex. The cationic and neutral complexes [B2(ttp)]2+ and [B2(ttp)] were characterised through a combination of spectroscopic data that is supported by DFT calculations on the porphine analogues. [source] Supramolecular Porphyrin Assemblies through Amidinium,Carboxylate Salt Bridges and Fast Intra-Ensemble Excited Energy TransferCHEMISTRY - A EUROPEAN JOURNAL, Issue 14 2004Joe Otsuki Prof. Abstract Well-defined supramolecular assemblies of Zn and free-base porphyrins are constructed through the formation of amidinium,carboxylate salt bridges. A one-to-one donor,acceptor pair and a four-to-one antenna-type assembly are investigated. The steady-state and time-resolved fluorescence measurements unequivocally showed that efficient singlet,singlet excited energy transfer from the Zn,porphyrin complex to the free-base porphyrin takes place in these assemblies. Indeed, the observed energy-transfer rates in both types of assemblies are much faster than those the Förster mechanism would suggest, implying the involvement of an intermolecular through-bond mechanism. [source] Thermally Activated Delayed Fluorescence from Sn4+,Porphyrin Complexes and Their Application to Organic Light Emitting Diodes , A Novel Mechanism for ElectroluminescenceADVANCED MATERIALS, Issue 47 2009Ayataka Endo Electroluminescence based on TADF, that is, thermally activated delayed fluorescence, is demonstrated in Sn4+,porphyrin complexes. On excitation by a short electrical pulse, prompt and delayed electroluminescence components were clearly observed. The delayed component was composed of both TADF and phosphorescence (see figure), and the TADF component significantly increased with increasing temperature. [source] In Vivo Phosphorescence Imaging of pO2 Using Planar Oxygen SensorsMICROCIRCULATION, Issue 6 2005PHILIPP BABILAS ABSTRACT Objective: Oxygen-dependent quenching of luminescence of metal porphyrin complexes has been used to image the pO2 distribution over tumor and normal tissue. Methods: An experimental setup is described using a platinum(II),octaethyl,porphyrin immobilized in a polystyrene matrix as transparent planar sensor. Results: Sensitivity over a broad range is high at low pO2 values (± 0.2 mm Hg at 0 mm Hg; ± 1.5 mm Hg at 160 mm Hg pO2). Due to intrinsically referencing via lifetime encoding there was no modification of the sensor response in vivo in the dorsal skinfold chamber model with amelanotic melanoma (A-MEL-3) in awake hamsters when compared to the in vitro calibration. pO2 measurements over normal tissue (25.8 ± 5.1 mm Hg) and tumor tissue (9.2 ± 5.1 mm Hg) were in excellent agreement with previous results obtained in this model using a surface multiwire electrode. Conclusions: Using the presented method the surface pO2 distribution can be mapped with a high temporal resolution of approximately 100 ms and a spatial resolution of at least 25 , m. Moreover, the transparent sensor allows the simultaneous visualization of the underlying microvasculature. [source] Gold (III) porphyrin complexes induce apoptosis and cell cycle arrest and inhibit tumor growth in colon cancerCANCER, Issue 19 2009Shuiping Tu MD Abstract BACKGROUND: Gold (III) compounds have exhibited favorable antitumor properties both in vitro and in vivo. In a previous study, the authors reported that the novel gold (III) complex 1a (gold 1a) exhibited strong cytotoxicity in some tumor cell lines. In the current study, the effect of gold 1a was investigated on colon cancer cells. METHODS: The cytotoxicity of gold 1a was determined by using the 3-(4,5-dimethyl-2-thihazyl)-2,5-diphenyl-2H-tetrazolium bromide method. Flow cytometry was used to detect apoptosis and cell cycle. The expression of protein was evaluated by Western blot assay. Tumor growth in vivo was evaluated in nude mice. RESULTS: Gold 1a exhibited marked cytotoxic effects in vitro to human colon cancer, and the concentration of drug required to inhibit cell growth by 50% compared with control (IC50) values ranged from 0.2 ,M to 3.4 ,M, which represented 8.7-fold to 20.8-fold greater potency than that of cisplatin. Gold 1a significantly induced apoptosis and cell cycle arrest and cleaved caspase 3, caspase 7, and poly(ADP-ribose) polymerase; released cytochrome C, and up-regulated p53, p21, p27, and Bax. In vivo, intraperitoneal injection of gold 1a at doses of 1.5 mg/kg and 3.0 mg/kg significantly inhibited tumor cell proliferation, induced apoptosis, and suppressed colon cancer tumor growth. An acute toxicology study indicated that gold 1a at effective antitumor concentrations did not cause any toxic side effects in mice. CONCLUSIONS: The current results suggested that gold 1a may be a new potential therapeutic drug for colon cancer. Cancer 2009. © 2009 American Cancer Society. [source] Diboryl and Diboranyl Porphyrin Complexes: Synthesis, Structural Motifs, and Redox Chemistry: Diborenyl Porphyrin or Diboranyl Isophlorin?CHEMISTRY - A EUROPEAN JOURNAL, Issue 21 2007Andre Weiss Dr. Abstract The syntheses of diboryl porphyrin complexes [(BX2)2(ttp)] (ttp: dianion of tetra- p -tolylporphyrin) and the BB single-bond diboranyl complexes [(BX)2(ttp)] (X=F, Cl, Br, I) are given. The former are prepared from the reactions of BX3 (X=F, Cl) with [Li2(ttp)] and the latter from B2Cl4 (X=Cl), the reaction of SbF3 with [(BCl)2(ttp)] (for X=F), and, in the cases of X=Br or I, in a remarkable reductive coupling reaction resulting directly from the reaction of BBr3 or BI3 with [Li2(ttp)]. Density functional theory (DFT) calculations on the thermochemical parameters for the reductive coupling reactions (and those calculated for related dipyrromethene complexes) indicate that a combination of the reducing ability of bromide and iodide ions combined with the constrained environment of the porphyrin ligand contribute to the driving force. The reductive coupling is also observed in the reaction of [(BCl2)2(ttp)] with nBuLi to give [(BnBu)2(ttp)], which was characterised crystallographically. The reaction of [(BCl)2(ttp)] with catechol gives a boron catecholato porphyrin complex, [B2(O2C6H4)(ttp)]. Chloride abstraction from [(BCl)2(ttp)] gives the planar dication [B2(ttp)]2+, whereas chemical reduction of [(BCl)2(ttp)] by using magnesium anthracenide gives a neutral complex, [B2(ttp)], in which the TTP ligand has been reduced by two electrons to give an unusual example of an isophlorin complex. The cationic and neutral complexes [B2(ttp)]2+ and [B2(ttp)] were characterised through a combination of spectroscopic data that is supported by DFT calculations on the porphine analogues. [source] Direct Probe of NO Vibration in the Naked Ferric Heme Nitrosyl ComplexCHEMPHYSCHEM, Issue 6 2008Barbara Chiavarino Dr. Vibrational features: The coupling of a free electron laser to a mass spectrometer measures the IR spectrum of iron porphyrin complexes of nitric oxide (see figure). Comparison of the photo-dissociation spectra, identifies the NO vibration at 1842 cm,1. [source] | |||||||||||||