Tetraphenylporphyrin Chloride Research Articles

X-ray Absorption Spectroscopy of Hemes and Hemeproteins in Solution: Multiple Scattering Analysis

A full quantitative analysis of Fe K-edge X-ray absorption spectra has been performed for hemes in two porphynato complexes, that is, iron(III) tetraphenylporphyrin chloride (Fe(III)TPPCl) and iron(III) tetraphenylporphyrin bis(imidazole) (Fe(III)TPP(Imid)2), in two protein complexes whose X-ray structure is known at atomic resolution (1.0 A), that is, ferrous deoxy-myoglobin (Fe(II)Mb) and ferric aquo-myoglobin (Fe(III)MbH2O), and in ferric cyano-myoglobin (Fe(III)MbCN), whose X-ray structure is known at lower resolution (1.4 A). The analysis has been performed via the multiple scattering approach, starting from a muffin tin approximation of the molecular potential. The Fe-heme structure has been obtained by analyzing independently the Extended X-ray Absorption Fine Structure (EXAFS) region and the X-ray Absorption Near Edge Structure (XANES) region. The EXAFS structural results are in full agreement with the crystallographic values of the models, with an accuracy of +/- 0.02 A for Fe-ligand distances, and +/-6 degrees for angular parameters. All the XANES features above the theoretical zero energy (in the lower rising edge) are well accounted for by single-channel calculations, for both Fe(II) and Fe(III) hemes, and the Fe-N p distance is determined with the same accuracy as EXAFS. XANES evaluations of Fe-5th and Fe-6th ligand distances are determined with 0.04-0.07 A accuracy; a small discrepancy with EXAFS (0.01 to 0.05 A beyond the statistical error), is found for protein compounds. Concerns from statistical correlation among parameters and multiple minima in the parameter space are discussed. As expected, the XANES accuracy is slightly lower than what was found for polarized XANES on Fe(III)MbCN single crystal (0.03-0.04 A), and states the actual state-of-the-art of XANES analysis when used to extract heme-normal parameters in a solution spectrum dominated by heme-plane scattering.

Baeyer-Villiger oxidation of ketones catalyzed by iron(III) meso-tetraphenylporphyrin chloride in the presence of molecular oxygen

Efficient selective oxidation of ketones to lactones by molecular oxygen with benzaldehyde as an oxygen acceptor, in the presence of metalloporphyrins, has been reported. Iron(III) meso-tetraphenylporphyrin chloride ( Fe ( TPP ) Cl ) showed excellent activity and selectivity for oxidation of cyclohexanones under mild conditions. Moreover, different factors influencing ketones oxidation, e.g. catalyst, solvent, temperature and additive, have been investigated. The turnover number (TON) of the Fe ( TPP ) Cl catalyst could reach up to 71000 in a large scale oxidation of cyclohexanone. A plausible mechanism of ketone oxidation by molecular oxygen in the presence of metalloporphyrins and benzaldehyde was proposed.

HPLC-ESI-MS/MS analysis of oxidized di-caffeoylquinic acids generated by metalloporphyrin-catalyzed reactions

This paper reports an HPLC-ESI-MS/MS investigation on the oxidation of 3,5- and 4,5- dicaffeoylquinic acid using iron(III) tetraphenylporphyrin chloride as catalyst. Two major mono-oxidised products of the quinic acid moiety have been identified for both compounds. However, only the 4,5-derivative afforded two different tri-oxo products. Thus, it seems that the oxidation pattern depends on the number and positions of the caffeic acid moieties present in caffeoylquinic acid molecules.

Iron Porphyrin Catalyzed N−H Insertion Reactions with Ethyl Diazoacetate

A series of metalloporphyrin complexes were surveyed as catalysts for carbene insertion from ethyl diazoacetate into the N−H bonds of amines. Iron(III) tetraphenylporphyrin chloride, Fe(TPP)Cl, was found to be an efficient catalyst for N−H insertion reactions with a variety of aliphatic and aromatic amines, with yields ranging from 68 to 97%. Primary amines were able to undergo a second insertion when another equiv of EDA was added by slow addition. N-Heterocyclic compounds were poor substrates, giving low yields or no N−H insertion products. Competition reactions and linear free energy relationships provided mechanistic insights for the insertion reaction. The relative rates for N−H insertion into para-substituted aniline derivatives correlated with Hammett σ+ parameters. Electron-donating groups enhanced the reaction, as indicated by the negative value of ρ (ρ = −0.66 ± 0.05, R2 = 0.93). These results are consistent with a rate-determining nucleophilic attack of the amine on an iron carbene complex. In ...

Plasma Polymerization of Manganese Chloride Tetraphenylporphyrin and Evaluation of the Thin Film

Plasma Polymerization of Manganese Chloride Tetraphenylporphyrin and Evaluation of the Thin Film

Plasma Polymerization of Manganese Chloride Tetraphenylporphyrin and Evaluation of the Thin Film

We have developed a polymer film by plasma polymerizing MnTPPCl and characterized it by various optical and electrical methods and studied its application as a chemical sensor to detect H2O2 and as a bio-sensor to detect glucose. For characterization of the plasma polymer we have used UV-Vis spectroscopy, IR, SEM, AFM, ESCA and cyclic voltammetry. Plasma polymerized MnTPPCl was found to be a promising candidate in the field of bio and chemical sensors.

DFT Study of Iron Tetraphenylporphyrin Chloride and Iron Pentafluorophenylporphyrin Chloride

The geometry optimizations and the single point energy calculations of iron tetraphenylporphyrin chloride Fe(TPP)Cl and iron tetraphenylporphyrin chloride (Fe(TPP)Cl), iron pentafluorophenylporphyrin chloride (Fe(TPPF20)Cl) were carried out by using the Density Functional Theory (DFT) UB3LYP with STO-3G* and 6-31G* basis sets, respectively. The electronic properties and the structures of high-lying molecular orbitals were analyzed in detail. The results show that partial spin is transferred from the Fe atom to the porphyrin ring and some electron with the spin opposite to the unpaired electron on the Fe atom is transferred from the porphyrin ring to the Fe atom. The - and -type bonding between the Fe atom and the porphyin ring cause the transfer. The fluorination enhances the electron transfer and the chemical stability of the complex. The high stability is important for the complex possessing high catalytic activity. The catalysis mechanism of oxygen molecule activation on the complex surface is also discussed based on the symmetry of the molecular orbitals.

Oxidative metabolism of 5- o-caffeoylquinic acid (chlorogenic acid), a bioactive natural product, by metalloporphyrin and rat liver mitochondria

Synthetic metalloporphyrins, in the presence of monooxygen donors, are known to mimic the various reactions of cytochrome P450 enzymes systems in the oxidation and oxygenation of various drugs and biologically active compounds. This paper reports an HPLC–MS–MS investigation of chlorogenic acid (CGA) oxidation by iodosylbenzene using iron(III) tetraphenylporphyrin chloride as catalyst. The oxidation products have been detected by sequential MS analyses. In addition, CGA was submitted to an in vitro metabolism assay employing isolated rat liver mitochondria. The single oxidized product obtained from mitochondrial metabolism corresponds to the major product formed by the metalloporphyrin-catalyzed reaction. These results indicate that biomimetic oxidation reactions, in addition to in vitro metabolism assays employing isolated organs/organelles, could replace some in vivo metabolism studies, thus minimizing the problems related to the use of a large number of living animals in experimental research.

Induced magnetic ordering in a molecular monolayer

Chemically tunable molecular magnets exhibit new and attractive properties, particularly in the field of spintronics. In this work, the magnetic interaction between a magnetized thin film cobalt substrate and adsorbed manganese(III)–tetraphenylporphyrin chloride (MnTPPCl) molecules has been studied by X-ray magnetic circular dichroism (XMCD). For MnTPPCl submonolayer coverages circular dichroism is observed at the Mn L III,II-edges. From temperature dependent studies and element-specific hysteresis curves, it is concluded that a net magnetization is induced on the complexed Mn in the adsorbed molecule. To our knowledge, this is the first clear evidence that exchange coupling between a large organic adsorbate and a ferromagnetic substrate are observable by XMCD.

Structure and catalytic activity of a manganese(iii) tetraphenylporpholactone

A manganese(III) complex of tetraphenylporpholactone, Mn(TPPL)Cl, was synthesized and characterized, including by single-crystal X-ray diffraction; the catalytic activity of this complex for olefin epoxidation reactions is compared with that of manganese(III) tetraphenylporphyrin chloride, Mn(TPP)Cl.

Effects of ion-carrier substituents on the potentiometric-response characteristics in anion-selective membrane electrodes based on iron porphyrins.

The potentiometric response characteristics with respect to salicylate anion of several membrane electrodes based on iron(III) tetraphenylporphyrin chloride (FeTPPCl) and derivatives with electrophilic and nucleophilic substituents, incorporated into plasticized polyvinylchloride (PVC) membranes were investigated. Complexes tetraphenyl porphyrin iron(III) chloride (FeTPPCl; A), tetrakis (4-methoxyphenyl) porphyrin iron(III) chloride (Fe(TOCH3PP)Cl; B), tetrakis (2,6-dichlorophenyl) porphyrin iron(III) chloride (Fe(TDClPP)Cl; C), tetrakis (4-nitrophenyl) porphyrin iron(III) chloride (Fe(TNO2PP)Cl; D), and tetrakis (pentafluorophenyl) porphyrin iron(III) chloride (Fe(TPFPP)Cl; E) were used as anion carriers in the membrane electrodes. The sensitivity, working range, detection limit, response mechanism, and selectivity of the membrane sensor toward interference shows a considerable dependence on the type of carrier substituent and the pH value of the sample solution. Potentiometric investigations in solutions of various pH show that the carrier complex containing fluoro substituents (E), which have very strong electron-accepting properties and a high ability to form hydrogen bonds, is capable of serving as a positively charged ionophore. Some other ionophores are capable of serving as both charged and neutral carriers under different conditions. The electrodes prepared in this work show super-Nernstian slopes with respect to salicylate concentration, which tend to a Nernstian response (slope near to -59 mV decade-1) upon an increase of the pH of the test solution. The results of UV/Vis absorption spectroscopy are used for interpretation of the formation of an oxene complex between salicylate and iron porphyrins.

Catalytic epoxidation of methyl linoleate

AbstractThe epoxidation of methyl linoleate was examined using transition metal complexes as catalysts. With a catalytic amount of methyltrioxorhenium (4 mol%) and pyridine, methyl linoleate was completely epoxidized by aqueous H2O2 within 4 h. Longer reaction times (6 h) were needed with 1 mol% catalyst loading. Manganese tetraphenylporphyrin chloride was found to catalyze the partial epoxidation of methyl linoleate. A monoepoxidized species was obtained as the major product (63%) after 20 h.

The determination of the standard Gibbs energies of ion transfer between water and heavy water by using the three-phase electrode approach

For the first time, the standard Gibbs energies of transfer of anions and cations across the nitrobenzene|heavy water interface are reported as measured by an electrochemical technique. The data have been obtained with the help of three-phase electrodes consisting of a nitrobenzene droplet that contains an electroactive compound (either decamethylferrocene to transfer anions or iron(III) tetraphenyl porphyrin chloride to transfer cations), a graphite electrode on the surface of which the droplet is attached, and a solution of the salts with the transferable ions in heavy water. The difference between these Gibbs energies of transfer and those of transfer between light water and nitrobenzene allows calculating the Gibbs energies of transfer between light water and heavy water. The latter vary in the interval from −0.50 to +0.50 kJ/mol with confidence intervals ranging from ±0.054 to ±0.117 kJ/mol.

Chromium(III) porphyrin as a selective ionophore in a salicylate-selective membrane electrode.

The construction, potentiometric response properties, and applications of a novel ion-selective electrode with high selectivity toward salicylate are described. Chromium(III) tetraphenylporphyrin chloride was used as ion carrier into plasticized PVC membrane. This ionophore is capable of serving as both a positively charged and neutral carrier, depending on the pH of the sample solution. The influence of several variables was investigated to optimize the potentiometric response and selectivity of the electrode. The resulting electrode demonstrates a near-Nernstian response over a wide range of salicylate concentration (10(-6)-10(-1) M). This electrode has a fast response time and micromolar detection limit and could be used over a wide pH range (3-9). The proposed electrode showed very high selectivity for salicylate over a number of common inorganic and organic anions. The specific interaction of salicylate with the central metal of porphyrin is described based on UV-visible absorption spectra. The electrode was successfully applied to the determination of salicylate in pharmaceutical preparations and clinical samples.

Synthesis of Ln(III) chloride tetraphenylporphyrin complexes.

The isolation and identification of the first examples of anhydrous lanthanide chloride tetraphenylporphyrin complexes have been described. The purple complexes were generated by the reaction of dilithiotetraphenylporphyrin bis(dimethoxyethane) with lanthanide trichloride tris(tetrahydrofuran) salts to yield the products in up to 85% yield. The crystal structures for the holmium and ytterbium complexes are also presented.

Potentiometric behavior of metalloporphyrin-based ion-selective electrodes: Use of silicone rubber matrix for serum chloride analysis

For the proper design of a miniaturized all-solid-state chloride-selective electrode for serum analysis with metalloporphyrin-based ionophores, the potentiometric behavior of four different metalloporphyrins, i.e., manganese(III) tetraphenylporphyrin chloride [Mn(TPP)Cl], manganese(III) octaethylporphyrin chloride [Mn(OEP)Cl], indium(III) tetraphenylporphyrin chloride [In(TPP)Cl] and indium(III) octaethylporphyrin chloride [In(OEP)Cl], doped in a one-component room temperature vulcanizing-type silicone rubber (SR) matrix were examined. Particular attention was paid to find a membrane formulation with minimal effect of salicylate because this interference is often the cause of a large positive error in serum chloride analysis. In general, the use of 10–20 wt% of plasticizer (e.g., o-nitrophenyl octyl ether (NPOE) and dibutyl sebacate (DBS)) was necessary for the ion carriers in SR to induce proper potentiometric response to chloride. On the other hand, In(TPP)Cl doped in SR matrix did not show any electrochemical activity regardless of the type of plasticizer employed. Mn(OEP)Cl or In(OEP)Cl doped in SR matrix with NPOE plasticizer exhibited super-Nernstian response (70.8 and 84.0 mV/pCl −, respectively), while those with DBS plasticizer show sub-Nernstian behavior. Of the two octaethyl porphyrins, the In(OEP)Cl-based membrane exhibited higher slope, 53.7 mV/decade, to chloride with reduced salicylate interference ( log K POT Cl −,sal − =1.1 with DBS). All-solid-state electrodes modified with In(OEP)Cl/SR/DBS membranes have been prepared and their utility for serum chloride measurement have been demonstrated.

Mössbauer Investigation on the Kinetics of the Pyrolysis of Iron(III) Tetraphenylporphyrin Chloride.

Mössbauer Investigation on the Kinetics of the Pyrolysis of Iron(III) Tetraphenylporphyrin Chloride.

Study by EPR and electronic spectroscopy of intermediates in iron porphyrin and iodosylbenzene reaction

The iron tetraphenylporphyrin chloride, (FeTPP)Cl), reaction with iodosylbenzene, (PhIO), was followed in different solvents by UV/Vis spectroscopy at 213 K and EPR spectroscopy at 4.2 K. The species 1 , (Fe IV-O-Fe IV(O)P .+), a dimeric active intermediate predominates in dichloromethane; 1 was evidenced by the large EPR radical signal at g = 2.006 (6K). Species 2 , (Fe IV(O)P .+), coexists, characterized by the less intense g = 3.950 EPR signal (6K). In methanoldichloromethane the electronic spectra shows the Soret band at 422 nm and visible bands at 542 nm and 580 nm, corresponding to formation of compound 3 , (PFe IVOH). The EPR spectra shows the weak g = 3.720 signal at 6 K, indicating species 2 coexistency. Species 1 have an important role in these unhindered iron porphyrin catalysts.

Photoinduced axial bond exchange reaction of dichlorophosphorus(V)tetraphenylporphyrin chloride: photochemical activation of central three-centre four-electron bond through the σ–π interaction

A novel photoinduced axial bond exchange reaction of dichlorophosphorus(V)tetraphenylporphyrin chloride in various alcohols affords axial dialkoxyphosphorus(V)tetraphenylporphyrin derivatives.

Pyrolysis behaviour of metalloporphyrins. Part 2.—A mössbauer study of pyrolysed FeIIItetraphenylporphyrin chloride

FeIII tetraphenylporphyrin chloride (FeCITPP) has been pyrolysed at different temperatures (450–850 °C) for different lengths of time (10–260 min). Some of the samples were mixed with carbon black in a 50/50 (w/w) proportion. Mossbauer spectra were obtained for these catalyst powders. The spectra reveal a number of different sites, occurring with different relative abundance depending on the pretreatment. XPS and electrochemical measurements have also been performed using the same samples. The electrocatalytic properties can be described as a function of the abundance of the various sites and the XPS data were used to support the interpretation.