Characterization by matrix-assisted laser desorption/ionization Fourier transform ion cyclotron resonance mass spectrometry of the major photoproducts of temoporfin (m-THPC) and bacteriochlorin (m-THPBC)

The photobleaching of 5,10,15,20-tetrakis(m-hydroxyphenyl)chlorin (temoporfin, m-THPC) and 5,10,15,20-tetrakis(m-hydroxyphenyl)bacteriochlorin (bacteriochlorin, m-THPBC) was studied in ethanol-water (1 : 99, v/v) and in physiological medium (phosphate-buffered saline, PBS) with or without fetal calf serum (FCS). m-THPC solution was irradiated with the laser radiation of 650 nm, whereas m-THPBC solution underwent two consecutive irradiations at 532 and 650 nm. The photoproducts were characterized by UV-visible absorption spectrophotometry and by matrix-assisted laser desorption/ionization (MALDI) coupled with Fourier transform ion cyclotron resonance mass spectrometry (FTICRMS). Independent of the solvent used, the phototransformation of either photosensitizer yielded the formation of 5,10,15,20-tetrakis (m-hydroxyphenyl)porphyrin (m-THPP) through a major dehydrogenation process.     

Radical polymerization of methyl methacrylate in the presence of Fe(III) and Co(III) porphyrins

The free-radical polymerization of methyl methacrylate in the presence of chlorine-containing complexes of Fe(III) with 5,10,15,20-tetrakis(3′,5′-di-tert-butylphenyl)porphyrin and 5,10,15,20-tetrakis(3′-butoxyphenyl)porphyrin, as well as in the presence of the acetate complex of Co(III) 5,10,15,20-tetrakis(3′,5′-di-tert-butylphenyl)porphyrin, has been investigated. The kinetic features of the process and the molecular mass characteristics of polymers are studied, and a feasible polymerization mechanism is proposed.     

Intracellular photobleaching of 5,10,15,20-tetrakis(m-hydroxyphenyl) chlorin (Foscan) exhibits a complex dependence on oxygen level and fluence rate

The understanding of photosensitizer photobleaching is important not only for mechanistic studies, but also for the development of monitoring techniques for clinical dosimetry in photodynamic therapy. In this study, we investigated the intracellular photobleaching of 5,10,15,20-tetrakis(m-hydroxyphenyl)chlorin (mTHPC, Foscan) in the murine macrophage cell line J774A.1, using quantitative fluorescence imaging microscopy, microspectrofluorometry and microspectrophotometry. Using 652 nm laser irradiation, it was found that mTHPC exhibits oxygen- and fluence rate-dependent intracellular photobleaching. The kinetics showed an inverse dose-rate behavior, i.e. a reduction of fluence rate resulted in more photobleaching at comparable fluences. The effect of deoxygenation was found to be more complex, with decreased bleaching at low fluence rates and increased bleaching at higher fluence rates. The intracellular formation of reactive oxygen species was measured using 2',7'-dichlorodihydrofluorescein diacetate. The results are analyzed in terms of competitive Type-I and Type-II mechanisms.     

MALDI-TOF mass spectrometric analysis for the characterization of the 5,10,15,20-tetrakis- (m-hydroxyphenyl)bacteriochlorin (m-THPBC) photoproducts in biological environment

Photoproducts formation upon irradiation (739 nm) of 5,10,15,20-tetrakis(m-hydroxyphenyl)bacteriochlorin (m-THPBC) in phosphate buffer saline (PBS) supplemented with human serum albumin (HSA) were studied by means of absorption spectroscopy and MALDI-TOF mass spectrometry. The experiments were performed with a freshly prepared PBS-HSA solution of m-THPBC and with a PBS-HSA m-THPBC solution incubated for 6 h at 37 degrees C. The incubation of m-THPBC solution leads to the dye monomerisation, whereas in the freshly prepared solution, m-THPBC is under an aggregated form. Regardless of the incubation condition, photobleaching experiments carried out by absorption spectroscopy demonstrate the degradation of the photosensitizer and its phototransformation in m-THPC. Moreover, m-THPC was the sole photoproduct detected using absorption spectroscopy. Together with a degradation of m-THPBC and formation of m-THPC, MALDI-TOF mass spectrometry evidenced several other photoinduced modifications. Photoproducts such as dihydroxy m-THPBC and dihydroxy m-THPC were detected in both conditions; however, the formation of hydroxylated photoproducts was significantly greater in incubated solution. In addition, small molecules arising from the degradation of the photosensitizer and identified as dipyrin derivatives and dipyrrolic synthon were observed.     

Controlling conformations and physical properties of meso-tetrakis(phenylethynyl)porphyrins by ring fusion: synthesis, properties and structural characterizations

The boron trifluoride-catalyzed Rothemund condensations of phenylpropargylaldehyde with 4,7-dihydro-4,7-ethano-2H-isoindole or 3,4-diethylpyrrole in dichloromethane at low temperature give 5,10,15,20-tetrakis(phenylethynyl)porphyrins bearing bicyclo[2.2.2]octadiene and octaethyl substituents, respectively. The former undergoes a retro Diels-Alder reaction to afford 5,10,15,20-tetrakis(phenylethynyl)benzoporphyrin quantitatively. The different conformations of the porphyrin periphery were determined by X-ray diffraction and their redox and spectroscopic properties have been investigated.     

Metal ion incorporation into n-methyl-5,10,15,20-tetrakis (4-sulfonatophenyl) porphine and its differential rates as applied to the kinetic determination of copper(II) and zinc(II) in serum

Metal ion incorporation intoN-methyl-5,10,15,20-tetrakis(4-sulfonatophenyl)porphine (N-CH₃TSPP) has been shown to be much faster than that for non-methylated porphyrins such as 5,10,15,20-tetrakis(4-sulfonatophenyl)porphine (TSPP). We have proposed a kinetic method, utilizing differential rate of metal ion incorporation into N-CH₃TSPP, for the determination of submicrogram amounts of copper(II) and zinc(II) in serum.     

Synthesis and spectrophotometric study of the acid-base and complexing properties of 2,3,7,8,12,13,17,18-Octaethyl-5,10,15,20-tetrakis(4-methoxyphenyl)porphyrin in acetonitrile

2,3,7,8,12,13,17,18-Octaethyl-5,10,15,20-tetrakis(4-methoxyphenyl)porphyrin has been synthesized, and its acid-base and complexing properties in the systems 1,8-diazabicyclo[5.4.0]undec-7-ene-acetonitrile, acetonitrile-Zn(OAc)₂, and 1,8-diazabicyclo[5.4.0]undec-7-ene-acetonitrile-Zn(OAc)₂ have been studied by spectrophotometry. Titration of 2,3,7,8,12,13,17,18-octaethyl-5,10,15,20-tetrakis(4-methoxyphenyl)porphyrin with 1,8-diazabicyclo[5.4.0]undec-7-ene is accompanied by successive deprotonation of the pyrrole nitrogen atoms with formation of the corresponding mono- and dianion. The overall acid dissociation constant of the title compound has been determined. The complexation of neutral and doubly deprotonated 2,3,7,8,12,13,17,18-octaethyl-5,10,15,20-tetrakis(4-methoxyphenyl)porphyrin with Zn(OAc)₂ has been studied, and kinetic parameters for the formation of the zinc complex according to the molecular and ionic mechanisms have been determined. Extra coordination of 1,8-diazabicyclo[5.4.0]undec-7-ene by the zinc complex of 2,3,7,8,12,13,17,18-octaethyl-5,10,15,20-tetrakis(4-methoxyphenyl)porphyrin.     

The Electrochemical Evaluation of the Antioxidant Activity of Substituted Tetraphenylporphyrins

Oxidative–reductive and antioxidant properties of 5,10,15,20-tetrakis(4-hydroxyphenyl)porphyrin, 5,10,15,20-tetrakis(4-aminophenyl)porphyrin, and 5,10,15,20-tetrakis(4-pentoxyphenyl)porphyrin in their reaction with the 2,2-diphenyl-1-picrylhydrazile free radical are studied. Two of the three abovelisted compounds, namely, 5,10,15,20-tetrakis(4-hydroxyphenyl)porphyrin and 5,10,15,20-tetrakis(4-aminophenyl) porphyrin, were found to possess antioxidant activity, the former’s antioxidant activity being higher, while 5,10,15,20-tetrakis(4-pentoxyphenyl)porphyrin showed no antioxidant properties. A probable mechanism of antioxidant activity of the studied porphyrins involves hydrogen homolytic detachment from functional substituent in phenyl ring and the hydrogen radical interaction with 2,2-diphenyl-1-picrylhydrazile.     

Catalytic activity and stability of anionic and cationic water soluble cobalt(II) tetraarylporphyrin complexes in the oxidation of 2-mercaptoethanol by molecular oxygen

The catalytic activity and stability of anionic cobalt(II) porphyrin complexes: 5,10,15,20-tetrakis(2,6-dichloro-3-sulfonatophenyl)porphyrinatocobalt(II), 5,10,15,20-tetrakis(2,4,6-trimethyl-3,5disulfonatophenyl)porphyrinatocobalt(II) and the cationic cobalt(II) porphyrin: 5,10,15,20-tetrakis[4-(diethylmethylammonio)phenyl]porphyrinatocobalt(II) tertraiodide have been investigated in the oxidation of 2-mercaptoethanol by dioxygen. All complexes were efficient catalysts for the auto-oxidation of 2-mercaptoethanol. The cationic cobalt(II) porphyrin has been found to be the most reactive catalyst. The rate of auto-oxidation of 2-mercaptoethanol catalysed by 5,10,15,20-tetrakis(2,4,6-trimethyl-3,5disulfonatophenyl)porphyrinatocobalt(II) has been found to increase with increasing the pH from 7 to 9 then decreased at higher pH. The rate constants of auto-oxidation reaction showed linear dependence on catalyst concentration and saturation kinetics in both 2-mercaptoethanol concentrations and dioxygen pressure. Anionic cobalt(II) porphyrin complexes showed higher stability than the cationic catalyst in repeat oxidation reactions. Immobilizing the anionic catalysts on ion exchange resin and supporting the cationic catalyst on clay mineral montmorillonite improved their stabilities towards oxidation.     

Synthesis,molecular structure,photophysical properties and spectroscopic characterization of new 1D-magnesium(II) porphyrin-based coordination polymer

Research on Chemical Intermediates - Chemical preparation, X-ray diffraction, spectral and photophysical studies were performed for H2TPBP (5,10,15,20-tetrakis[4 (benzoyloxy)phenyl] porphyrin),...     

New class of potent catalysts of O2.-dismutation. Mn(III) ortho-methoxyethylpyridyl- and di-ortho-methoxyethylimidazolylporphyrins

Three new Mn(III) porphyrin catalysts of O2.-dismutation (superoxide dismutase mimics), bearing ether oxygen atoms within their side chains, were synthesized and characterized: Mn(III) 5,10,15,20-tetrakis[N-(2-methoxyethyl)pyridinium-2-yl]porphyrin (MnTMOE-2-PyP(5+)), Mn(III)5,10,15,20-tetrakis[N-methyl-N'-(2-methoxyethyl)imidazolium-2-yl]porphyrin (MnTM,MOE-2-ImP(5+)) and Mn(III) 5,10,15,20-tetrakis[N,N'-di(2-methoxyethyl)imidazolium-2-yl]porphyrin (MnTDMOE-2-ImP(5+)). Their catalytic rate constants for O2.-dismutation (disproportionation) and the related metal-centered redox potentials vs. NHE are: log k(cat)= 8.04 (E(1/2)=+251 mV) for MnTMOE-2-PyP(5+), log k(cat)= 7.98 (E(1/2)=+356 mV) for MnTM,MOE-2-ImP(5+) and log k(cat)= 7.59 (E(1/2)=+365 mV) for MnTDMOE-2-ImP(5+). The new porphyrins were compared to the previously described SOD mimics Mn(III) 5,10,15,20-tetrakis(N-ethylpyridinium-2-yl)porphyrin (MnTE-2-PyP(5+)), Mn(III) 5,10,15,20-tetrakis(N-n-butylpyridinium-2-yl)porphyrin (MnTnBu-2-PyP(5+)) and Mn(III) 5,10,15,20-tetrakis(N,N'-diethylimidazolium-2-yl)porphyrin (MnTDE-2-ImP(5+)). MnTMOE-2-PyP(5+) has side chains of the same length and the same E(1/2), as MnTnBu-2-PyP(5+)(k(cat)= 7.25, E(1/2)=+ 254 mV), yet it is 6-fold more potent a catalyst of O2.-dismutation , presumably due to the presence of the ether oxygen. The log k(cat)vs. E(1/2) relationship for all Mn porphyrin-based SOD mimics thus far studied is discussed. None of the new compounds were toxic to Escherichia coli in the concentration range studied (up to 30 microM), and protected SOD-deficient E. coli in a concentration-dependent manner. At 3 microM levels, the MnTDMOE-2-ImP(5+), bearing an oxygen atom within each of the eight side chains, was the most effective and offered much higher protection than MnTE-2-PyP(5+), while MnTDE-2-ImP(5+) was of very low efficacy.     

Synthesis and nanostructures of 5,10,15,20-tetrakis(4-piperidyl)porphyrin

A new water-soluble porphyrin, 5,10,15,20-tetrakis(4-piperidyl)porphyrin (T(4-Pip)P), has been synthesized. T(4-Pip)P is related to the extensively studied water-soluble porphyrin 5,10,15,20-tetrakis(4-pyridyl)porphyrin (T(4-Py)P) but has substituents with different electronic and hydrogen-bonding properties and is soluble over a much larger pH range due to the higher pK_a of its conjugate acid T(4-H-Pip)P⁴⁺. Investigations of the ionic self-assembly reactions of T(4-H-Pip)P⁴⁺ with anionic water-soluble porphyrins reveal that it forms nanoscale materials.     

Cellular uptake and photocytotoxicity of glycoconjugated chlorins in HeLa cells

Eight 5,10,15,20-tetrakis[3- or 4-(beta-D-glycopyranosyloxy)phenyl]chlorins were synthesized by means of the Whitlock method with diimide reduction and purified by reversed-phase thin layer chromatography (RP-TLC). All compounds were characterized by (1)H NMR spectroscopy, electron-spray ionization time-of-flight mass spectrometry (ESI-TOF MS), and UV-Vis spectroscopy. ESI-TOF MS could detect the 2H difference in molecular weight between a glycoconjugated chlorin and its corresponding porphyrin (i.e., 5,10,15,20-tetrakis[3- or 4-(beta-D-glycopyranosyloxy)phenyl]porphyrin). The cellular uptake of the eight chlorins was evaluated in HeLa cells. All glycoconjugated chlorins showed higher cellular uptake than tetraphenylporphyrin tetrasulfonic acid (TPPS), and 5,10,15,20-tetrakis[3-(beta-D-xylopyranosyloxy)phenyl]chlorin showed 50-fold higher uptake than TPPS. The photocytotoxicity of 5,10,15,20-tetrakis[3-(beta-D-glucopyranosyloxy)phenyl]chlorin, 5,10,15,20-tetrakis[3-(beta-D-xylopyranosyloxy)phenyl]chlorin and TPPS towards HeLa cells was examined at the concentration of 2x10(-7) M (mol/dm(3)). These photosensitizers had no cytotoxicity in the dark, but their photocytotoxicity decreased in the order of 5,10,15,20-tetrakis[3-(beta-D-glucopyranosyloxy)phenyl]chlorin>5,10,15,20-tetrakis[3-(beta-D-xylopyranosyloxy)phenyl]chlorin>TPPS. The results indicate that the photocytotoxicity is not related simply to cellular uptake.     

Kinetic Study of the Redox Properties of [5,10,15,20-Tetrakis(2,5-dimethoxyphenyl)porphyrinato]cobalt(II) in the Reaction with Hydrogen Peroxide

Russian Journal of General Chemistry - The reaction of [5,10,15,20-tetrakis(2,5-dimethoxyphenyl)porphyrinato]cobalt(II) with hydrogen peroxide in acetonitrile at 298 K has been studied by spectral...     

Synthesis and Antimicrobial Activity of a Pyridine Complex of (Acetato)[5,10,15,20-tetrakis(<Emphasis Type="Italic">N</Emphasis>-methylpyridin- 4-yl)porphinato]manganese(III) Tetratosylate

Aiming at preparation of new biologically active donor?acceptor complexes, a water-soluble manganese(III) complex with 5,10,15,20-tetrakis(N-methylpyridin-4-yl)porphine tetratosylate was synthesized and its reaction with pyridine was studied by spectrophotometry using the molar ratio method. In water a 1: 1 donor?acceptor complex with pyridine is formed. The chemical structure of the compounds was established by spectral methods. (Acetato)[5,10,15,20-tetrakis(N-methylpyridin-4-yl)porphinato]manganese(III) tetratosylate and especially its donor?acceptor complex with pyridine showed an antifungal activity against Candida albicans.     

HPLC-electrospray mass spectrometry for the analysis of temoporfin-poly(ethylene glycol) conjugates

The photodynamic therapeutic agent temoporfin, 5,10,15,20-tetra(m-hydroxyphenyl)chlorin (m-THPC) conjugated with poly(ethylene glycol) 2000 (PEG), has been analysed by high performance liquid chromatography (HPLC), linked to electrospray ionisation mass spectrometry (ESI-MS). Sufficient separation of m-THPC-PEG 2000 oligomers was achieved, enabling determination of molecular mass. The use of ESI-MS alone could not achieve this, because of too great a complexity in the mass spectrum, resulting from the presence of four PEG 2000 side chains with a wide molecular mass distribution. The technique is applicable to similar PEG conjugated compounds.     

Androgynous porphyrins. Silver(II) quinoxalinoporphyrins act as both good electron donors and acceptors

The metal-centered and macrocycle-centered electron-transfer oxidations and reductions of silver(II) porphyrins were characterized in nonaqueous media by electrochemistry, UV-vis spectroelectrochemistry, EPR spectroscopy, and DFT calculations. The investigated compounds are {5,10,15,20-tetrakis(3,5-di-tert-butylphenyl)porphyrinato}silver(II), {5,10,15,20-tetrakis(3,5-di-tert-butylphenyl)quinoxalino[2,3-b']porphyrinato}silver(II), {5,10,15,20-tetrakis(3,5-di-tert-butylphenyl)bisquinoxalino[2,3-b':7,8-b']porphyrinato}silver(II), and {5,10,15,20-tetrakis(3,5-di-tert-butylphenyl)bisquinoxalino[2,3-b':12,13-b']porphyrinato}silver(II). The first one-electron oxidation and first one-electron reduction both occur at the metal center to produce stable compounds with Ag(III) or Ag(I) metal oxidation states, irrespective of the type of porphyrin ligand. The electrochemical HOMO-LUMO gap, determined by the difference in the first oxidation and first reduction potentials, decreases by introduction of quinoxaline groups fused to the Ag(II) porphyrin macrocycle. This provides a unique androgynous character to Ag(II) quinoxalinoporphyrins that enables them to act as both good electron donors and good electron acceptors, something not previously observed in other metalloporphyrin complexes. The second one-electron oxidation and second one-electron reduction of the compounds both occur at the porphyrin macrocycle to produce Ag(III) porphyrin pi-radical cations and Ag(I) porphyrin pi-radical anions, respectively. The macrocycle-centered oxidation potentials of each quinoxalinoporphyrin are shifted in a negative direction, while the macrocycle-centered reduction potentials are shifted in a positive direction as compared to the same electrode reactions of the porphyrin without the fused quinoxaline ring(s). Both potential shifts are due to a stabilization of the radical cations and radical anions by pi-extension of the porphyrin macrocycle after fusion of one or two quinoxaline moieties at the beta-pyrrolic positions of the macrocycle. Introduction of quinoxaline groups fused to the Ag(II) porphyrin macrocycle provides a unique androgynous character to Ag(II) quinoxalinoporphyrins that enables them to act as both good electron donors and good electron acceptors.     

Halogen atom effect on photophysical and photodynamic characteristics of derivatives of 5,10,15,20-tetrakis(3-hydroxyphenyl)porphyrin

Brominated and iodinated derivatives of 5,10,15,20-tetrakis(3-hydroxyphenyl)porphyrin were synthesised directly from the corresponding aldehydes. Photophysical and photochemical properties, singlet oxygen formation quantum yields, photobleaching and log P were measured. Cellular uptake measurements and cytotoxicity assays on WiDr and A375 tumour cell lines were performed. 5,10,15,20-Tetrakis(2-bromo-5-hydroxyphenyl)porphyrin showed the best cytotoxicity with values of IC(50) of 113 nM over WiDr cells and 52nM over A375 cells.     

Immobilization of porphyrins in poly(hydroxymethylsiloxane)

Three tetracationic porphyrins differing in the position of charged nitrogen atoms on the peripheral substituents — 5,10,15,20-tetrakis(N-methylpyridinium-4-yl)porphyrin (TMPyP4), 5,10,15,20-tetrakis(N-methylpyridinium-2-yl)porphyrin (TMPyP2), 5,10,15,20-tetrakis(4-trimethylammoniophenyl) porphyrin (TMAPP), and hydrophobic 5,10,15,20-tetraphenylporphyrin (TPP), were immobilized by adsorption and encapsulation in poly(hydroxymethylsiloxane) (PHOMS). The so prepared porphyrin-PHOMS composites were characterized by porosimetry, scanning electron microscopy, fluorescence and diffuse reflectance UV-VIS spectroscopy. It was found that porphyrins are immobilized in the PHOMS matrix in the free base monomer form Their irradiation produced singlet oxygen O₂(¹Δ_g) with the lifetime of 10–30 μs.     

Methoxy-isoporphyrins of water-soluble porphyrins: synthesis,characterization and electrochemical properties

Abstract

Methoxy-isoporphyrins of zinc [5,10,15,20-tetrakis(4-sulfonatophenyl)]porphyrin, ZnTSPP (1a) and zinc [5,10,15,20-tetrakis(4-carboxyphenyl)]porphyrin, ZnTCPP (1b) have been synthesized and characterized using standard spectroscopic techniques (Uv-visible, ¹H NMR) , ESI-mass spectrometry and powder X-ray diffraction studies. The isoporphyrins [5-(methoxy)-5,10,15,20-tetrakis(4-sulfonatophenyl)-5H,15H-porphinato]zinc(II) (2a) and [5-(methoxy)-5,10,15,20-tetrakis(4-carboxyphenyl)-5H,21H-porphinato]zinc(II) (2b) are formed due to nucleophilic attack of the methanol to the zinc porphyrin dication. Ceric ammonium nitrate (CAN) was used to oxidize zinc porphyrin and to form zinc porphyrin dication. The electronic spectra of the isoporphyrin complexes 2a and 2b exhibit an intense peak at near IR region . Electrochemical measurements of the synthesized isoporphyrins showed a typical irreversible reduction peak at lower potential. S-containing nucleophiles, which work as reducing agents, convert the zinc isoporphyrins to their parent porphyrins, which supports the electrochemical observations. Their structural properties have been studied using powder X-ray diffraction. The luminescence properties of isoporphyrins were compared with the parent zinc porphyrins.