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Showing papers on "Porphyrin published in 1998"


Journal ArticleDOI
TL;DR: The history of the first generation PDT agent hematoporphyrin derivative is described in detail in this article, where the optical spectra of porphyrins and chlorins are analyzed.

916 citations


Journal ArticleDOI
TL;DR: The occurrence, classification, and study of nonplanar porphyrins in proteins and synthetic non Planar Porphyrin analogs are reviewed.
Abstract: Nonplanar distortions of tetrapyrroles are prevalent in the hemes of hemoproteins, the pigments of photosynthetic proteins, and cofactor F430 of methylreductase. The nonplanarity of these porphyrin cofactors is currently believed to influence factors in the biological activity of the proteins, in part, because the porphyrin deformations are often conserved within functional classes of proteins. The occurrence, classification, and study of nonplanar porphyrins in proteins and synthetic nonplanar porphyrin analogs are reviewed.

754 citations


Journal ArticleDOI
TL;DR: In this paper, the interactions of several water-soluble ionic porphyrins with different ionic or neutral surfactants in aqueous solutions were studied as a function of surfactant concentration.
Abstract: The interactions of several water-soluble ionic porphyrins with different ionic or neutral surfactants in aqueous solutions were studied as a function of surfactant concentration. The interaction leads to the formation of porphyrin aggregates and/or micelle-encapsulated monomers with the exception of those porphyrin−surfactant pairs for which the interaction is Coulombically repulsive. The premicellar surfactant−porphyrin aggregate is identified by absorption and fluorescence spectroscopy, fluorescence lifetime and anisotropy, and resonance light scattering. The spectroscopic results are used to characterize the premicellar aggregates as J-type, H-type, or nonspecific aggregates. All premicellar surfactant−porphyrin aggregates dissociate to form micelle-encapsulated monomers when the surfactant concentration approaches cmc (critical micellar concentration). The interaction of tetrakis-(4-sulfanatophenyl)porphine dianion (H4TPPS2-) at pH <3.5 with cetyltrimethylammonium cation (CTAB) is described by the fo...

722 citations


Journal ArticleDOI
TL;DR: In this paper, a light-harvesting array containing one, two, or eight boron-dipyrrin (BDPY) pigments and one porphyrin (free base or Zn chelate) has been synthesized using a modular building block approach.
Abstract: Light-harvesting arrays containing one, two, or eight boron-dipyrrin (BDPY) pigments and one porphyrin (free base or Zn chelate) have been synthesized using a modular building block approach. The reaction of pyrrole and 4-(BDPY)benzaldehyde or 3,5-bis(BDPY)benzaldehyde, prepared by Pd-mediated ethynylation with the corresponding iodo-benzaldehydes, affords the desired BDPY-porphyrin array in yields of 10−58%. The arrays are soluble in organic solvents and have been characterized by static and time-resolved absorption and fluorescence spectroscopy. The blue-green BDPY absorption complements spectral coverage of the porphyrin chromophores and rivals the intensity of the porphyrin Soret band when eight BDPY accessory pigments are present. Efficient energy transfer from the BDPY pigment(s) to the porphyrin (free base or Zn-chelate) is observed in arrays containing one or two (>90%) or eight (>85%) accessory pigments per porphyrin. Biphasic excited-state decay behavior is exhibited by the BDPY pigments in isol...

387 citations


Journal ArticleDOI
TL;DR: Of the three sulfonated porphyrins investigated only TPPS4 was efficiently incorporated into leukocytes, and in the incubation solvent this dye was in monomeric and neutral form.
Abstract: The incorporation of the five following porphyrins: meso-tetra(4-phenyl)porphyrin (TPP); meso-tetra(4-sulfonato-phenyl)porphyrin (TPPS4); meso-tetra(4-naphthyl)porphyrin (TNP); tri-sulfo-tetra-phenyl porphyrin (TPPS3) and tetra-sulfonato-naphthyl porphyrin (TNPS4) into human blood cells was investigated using flow cytometry, and absorption and emission spectroscopy. The percentage of stained cells, measured in a fluorescence cytometer, provided information on the efficiency of incorporation of fluorescent dye molecules into different types of cells. The yield of the incorporation of a dye was dependent on the type of dye and the solvent used for cell incubation. The degree of dye aggregation and ionization varied with the incubation medium, but dye molecules incorporated into cells seemed to be restricted to those in the monomeric state, exhibiting similar fluorescence yield. Of the three sulfonated porphyrins investigated only TPPS4 was efficiently incorporated into leukocytes. In the incubation solvent, this dye was in monomeric and neutral form. TPPS3 which was also in monomeric form, practically was not incorporated into cells. TPP and TNP dissolved in 5% aqueous dimethyl sulfoxide were present mostly in aggregated forms but they penetrated the cells with a high efficiency.

331 citations


Journal ArticleDOI
TL;DR: The out-of-plane distortions of porphyrins in hemoproteins are characterized by displacements along the lowest-frequency out- of-plane normal coordinates of the D4h-symmetric macrocycle, and x-ray crystal structures are analyzed using a computational procedure developed for determining these orthogonal displacements.

305 citations


Journal ArticleDOI
TL;DR: Twenty-one components self-assemble to form the large (ca. 25 nm2 ), planar porphyrin arrays of type 1: four dipyridylporphyrins, four tripyridolporphYRins, one tetrapyrIDylporPhyrin, and twelve PdCl2 units.
Abstract: Twenty-one components self-assemble to form the large (ca. 25 nm2 ), planar porphyrin arrays of type 1: four dipyridylporphyrins, four tripyridylporphyrins, one tetrapyridylporphyrin, and twelve PdCl2 units.

262 citations


Journal ArticleDOI
TL;DR: A series of dendrimer porphyrins ((L5)nP, n = 1−4), which bear different numbers (n) of five-layered dendron subunits at the meso-positions of a porphrin, were synthesized in this article.
Abstract: A series of dendrimer porphyrins ((L5)nP, n = 1−4), which bear different numbers (n) of five-layered dendron subunits (L5) at the meso-positions of a porphyrin, were synthesized. Upon excitation of the dendron subunits in CH2Cl2 at 20 °C, (L5)nP showed an intramolecular singlet energy transfer from the dendron subunits to the porphyrin core, where tetrasubstituted (L5)4P with a spherical morphology exhibited a much higher energy transfer quantum yield (ΦENT = 80.3%) than partially substituted (L5)1P−(L5)3P (10.1−31.6%). Fluorescence depolarization characteristics of (L5)4P indicated that the excitation energy migrates very efficiently over the continuous dendrimeric array of dialkoxybenzyl building units within the lifetime of the excited state. Consequently, the probability of energy transfer to the porphyrin core was enhanced.

248 citations


Journal ArticleDOI
TL;DR: In this paper, photoacoustic calorimetry was used to measure the quantum yields of singlet molecular oxygen production by the triplet states of tetraphenylporphyrin (TPP), ZnTPP and CuTPP in toluene, yielding values of 0.67 0.14, 0.68 0.19 and 0.03 0.07 quantum yield.
Abstract: Photoacoustic calorimetry was used to measure the quantum yields of singlet molecular oxygen production by the triplet states of tetraphenylporphyrin (TPP), ZnTPP and CuTPP in toluene, yielding values of 0.67 0.14, 0.68 0.19 and 0.03 0.01, respectively. We show that a novel dichlorophenyl derivative of ZnTPP is capable of singlet-oxygen production with a 0.90 0.07 quantum yield. The synthesis and characterisation of a new photostable chlorin with high absorptivity in the red that is capable of singlet-oxygen production with 0.54 0.06 quantum yield is described. Our results suggest that chlorinated chlorins may be interesting new sensitisers for photodynamic therapy.

209 citations


Journal ArticleDOI
TL;DR: To assess the potential of using porphyrins as probes for these structures, the interaction of tetrakis(4-N-methylpyridyl)porphine (H2TMPyP) with the simple quadruplex formed by T4G4 and with the duplex formed by CGCGATATCGCG is investigated.
Abstract: We have recently reported the cation-induced self-assembly of DNA oligomers of the general sequence C4T4G4T1-4G4 into high-molecular weight multistranded structures [Marotta, S.P., Tamburri, P.A., and Sheardy, R.D. (1996) Biochemistry 35, 10484-10492]. The architecture of the proposed structure consists of a series of four leafed G4 tetrads tethered together via one or two T1-4 strands and thus resembles a long four-sided hollow tube with periodic "pockets". These pockets possess electrostatic, hydrogen bonding, and hydrophobic contact points and should be ideal candidates for the binding of small molecules. To assess the potential of using porphyrins as probes for these structures, we have investigated the interaction of tetrakis(4-N-methylpyridyl)porphine (H2TMPyP) with the simple quadruplex formed by T4G4 and with the duplex formed by CGCGATATCGCG. Visible absorption, circular dichroism, and fluorescent energy transfer studies indicate that H2TMPyP binds to both the duplex and quadruplex via intercalation at low [porphyrin]/[DNA molecule] ratios, i.e., in the presence of excess potential DNA binding sites. Analyses of Scatchard plots show that H2TMpyP binds with high affinity to both DNA secondary structures but binds to the quadruplex with an affinity 2 times greater than that of the duplex.

205 citations


Journal ArticleDOI
TL;DR: Treatment with 8‐aminolevulinic acid methylester leads to a preferential enrichment of porphyrins within lesional skin, suggesting that application of free δ‐aminolenic acid may be more effective in sensitizing solar keratoses.
Abstract: Topically applied delta-aminolevulinic acid is used efficiently for the treatment of solar keratoses by photodynamic therapy. Recent animal studies suggest that porphyrin sensitization of epithelial tissue is improved by using esters rather than free delta-aminolevulinic acid. The present study examines porphyrin metabolite formation after topical application of delta-aminolevulinic acid or delta-amino-levulinic acid methylester in human solar keratoses versus adjacent normal skin. Level of total porphyrins, porphyrin metabolites and protein were measured in skin samples excised after 1 and 6 h. Higher levels of porphyrins were observed in solar keratoses than in normal skin with both substances. Maximum porphyrin levels were present in solar keratoses treated with delta-aminolevulinic acid for 6 h. However, the ratio of porphyrins in solar keratoses versus adjacent normal skin was higher with delta-aminolevulinic acid methylester. The pattern of porphyrins showed no significant difference between normal and afflicted skin, protoporphyrin being predominant. The results suggest that application of free delta-aminolevulinic acid may be more effective in sensitizing solar keratoses. However, treatment with delta-aminolevulinic acid methylester leads to a preferential enrichment of porphyrins within lesional skin.

Journal ArticleDOI
TL;DR: In this paper, two pyrrole rings participate in the aromatic structure of porphyrin, and a 22 π-electron description is given, which is better than the usual [18]annulene representation.
Abstract: Two pyrrole rings participate in the aromatic structure of porphyrin. Hence, a 22 π-electron description is better than the usual [18]annulene representation. The dianion and the metal complex system favor different electronic structures.

Journal ArticleDOI
TL;DR: Up to 14 porphyrin rings are present in the title compounds 1, which are readily available with high regioselectivity from linear nickel-zinc porphyrs, and upon irradiation with light a rapid energy transfer from the peripheral porphirin rings to the diporphyrIn core takes place.
Abstract: Up to 14 porphyrin rings are present in the title compounds 1, which are readily available with high regioselectivity from linear nickel–zinc porphyrins. Upon irradiation with light a rapid energy transfer from the peripheral porphyrin rings to the diporphyrin core takes place.

Journal ArticleDOI
24 Jun 1998-Langmuir
TL;DR: In this paper, four cobalt porphyrins were adsorbed on graphite electrodes and used to catalyze the electroreduction of O2 by four electron reduction.
Abstract: Four cobalt porphyrins were adsorbed on graphite electrodes and used to catalyze the electroreduction of O2. The two porphyrins without substituent groups in the meso positions of the porphyrin ring operated at the most positive potentials and catalyzed the reduction of O2 to both H2O2 and H2O, but the H2O did not result from significant reduction of H2O2. The porphyrins containing meso substituents catalyzed only the reduction of O2 to H2O2. The catalysts that accomplish the four-electron reduction of O2 are argued to consist of dimeric (or higher oligomeric) forms of the adsorbed porphyrins. The present results and those of two recent related studies1,2 indicate that the presence of only hydrogen or small alkyl groups in the meso positions of porphyrin rings facilitates the spontaneous formation of van der Waals dimers with greater catalytic activity for the reduction of O2 by four electrons. Such cobalt porphyrins were also found to be unusually active catalysts for the electro-oxidation of H2O2.

Journal ArticleDOI
TL;DR: In this paper, the ability of a dendritic shell to afford site isolation to a porphyrin core was evaluated using electron-transfer experiments with a series of POR core dendrimers.
Abstract: The ability of a dendritic shell to afford site isolation to a porphyrin core was evaluated using electron-transfer experiments with a series of porphyrin-core dendrimers. Cyclic voltammograms show that surrounding a porphyrin site with even a small generation (G ∼ 2) dendrimer can significantly lower the rate of interfacial electron transfer, ostensibly by decreasing the proximity of the porphyrin core to the electrode surface. This inhibition of electron transfer is more pronounced when larger generation dendrimers are employed. While a significant measure of site isolation is achieved with respect to an electrode surface, no hindrance to penetration of a small molecule is afforded by the dendritic shell surrounding the porphyrin core, an encouraging result if dendrimers are to be designed as macromolecular hosts with a functioning catalyst at the core. Stern−Volmer analysis was used to investigate the accessibility of a small molecule, benzylviologen, to the porphyrin core. For generations 1−3, the den...

Journal ArticleDOI
TL;DR: The photochemistry of a molecular triad consisting of a porphyrin (P) covalently linked to a carotenoid polyene (C) and a fullerene derivative (C60) has been studied at 20 K by time-resolved EPR sp...
Abstract: The photochemistry of a molecular triad consisting of a porphyrin (P) covalently linked to a carotenoid polyene (C) and a fullerene derivative (C60) has been studied at 20 K by time-resolved EPR sp...


Journal ArticleDOI
TL;DR: Despite their larger separation, the porphyrin groups in 1 are more strongly conjugated than in analogous compounds in which butadiyne is the bridging unit, which results in a bathochromic shift in its absorption and emission spectra.
Abstract: Despite their larger separation, the porphyrin groups in 1 are more strongly conjugated than in analogous compounds in which butadiyne is the bridging unit. This stronger electronic coupling in 1 results in a bathochromic shift in its absorption and emission spectra.

Journal ArticleDOI
TL;DR: It is demonstrated that FePPIX is bound to the cell in the mu-oxo dimeric form, [Fe(III)PPIX]2O, and that the iron porphyrin pigment is also composed of this material.
Abstract: Mossbauer spectroscopy was used to re-evaluate iron protoporphyrin IX, FePPIX, binding and the chemical nature of the black iron porphyrin pigment of Porphyromonas gingivalis. We demonstrate that FePPIX is bound to the cell in the mu-oxo dimeric form, [Fe(III)PPIX]2O, and that the iron porphyrin pigment is also composed of this material. P. gingivalis also assimilated monomeric Fe(II)- and Fe(III)PPIX into mu-oxo dimers in vitro. Scatchard analysis revealed a greater binding maximum of cells for mu-oxo dimers than for monomeric Fe(III)-or Fe(II)PPIX, although the relative affinity constant for the dimers was lower. Formation of [Fe(III)PPIX]2O via reactions of Fe(II)PPIX with oxygen, and its toxic derivatives, would serve as an oxidative buffer and permit P. gingivalis and other black-pigmenting anaerobes to engender and maintain a local anaerobic environment. Tying up of free oxygen species with iron protoporphyrin IX would also reduce and limit Fe(II)PPIX-mediated oxygen-radical cell damage. More importantly, formation of a cell-surface mu-oxo dimer layer may function as a protective barrier against assault by reactive oxidants generated by neutrophils. Selective interference with these mechanisms would offer the possibility of attenuating the pathogenicity of P. gingivalis and other iron protoporphyrin IX-binding pathogens whose virulence is regulated by this reactive molecule.


Journal ArticleDOI
TL;DR: The 3 + 1 approach for porphyrinoid synthesis is an excellent methodology for preparing aromatic 6-membered ring subunit analogues as mentioned in this paper, and it has been shown to yield 35−52% yield.
Abstract: The “3 + 1” route for porphyrinoid synthesis is an excellent methodology for preparing aromatic porphyrin analogues with six-membered ring subunits. Condensation of 5-formylsalicylaldehyde with tripyrranes 15, 24, and 25 in the presence of 5% TFA-dichloromethane, followed by neutralization and oxidation with DDQ, afforded a series of semiquinone-containing porphyrinoids 12, 26, and 27 in 35−52% yield. In these novel systems, the macrocycle achieves aromatization by undergoing a keto−enol tautomerization whereby the phenolic subunit is transformed so that the inner three carbon atoms become part of the 18 π-electron aromatic core, whereas the outer carbons generate an enone unit. The aromatic nature of these “oxybenziporphyrins” is evident from their porphyrin-like electronic spectra and the presence of powerful diamagnetic ring currents in their proton NMR spectra, where the inner CH is shifted upfield to δ = −7 ppm, whereas the external meso-protons appear downfield between 8.8 and 10.3 ppm. The presence...

Journal ArticleDOI
TL;DR: A series of conjugated porphyrin oligomers have been prepared and the evolution in their electronic properties is discussed; the crystal structure of the dimer is presented, as well as the MALDI TOF mass spectrum of the hexamer as mentioned in this paper.

Journal ArticleDOI
TL;DR: In this article, a new type of porphyrin array was synthesized by coupling of six porphrin moieties to a central benzene core via an ether linkage, and the resulting porphryin supermolecule has a diameter up to 80 A and a mass of 8500 daltons.
Abstract: A new type of porphyrin array has been synthesized by the coupling of six porphyrin moieties to a central benzene core via an ether linkage. The resulting porphryin supermolecule has a diameter up to 80 A and a mass of 8500 daltons. In solution, the six porphyrins around the central benzene ring arrange themselves into three sets of offset overlapping dimers, which are rapidly interconverting at room temperature. Solution UV−vis and fluorescence studies, however, indicate that there are no electronic interactions between the individual porphyrin molecules. Upon spreading a chloroform solution of these porphyrin molecules on a surface, they self-assemble to form ring-shaped architectures on a micrometer scale. Near-field scanning optical microscopy studies reveal that the porphyrin moieties within the rings have an ordered arrangement with respect to their position in the ring after the sample has been annealed at 80 °C for 2 days.

Journal ArticleDOI
TL;DR: In this paper, a quantitative intramolecular energy transfer from the anthracene donor to the emitting porphyrin acceptor through the oligothiophene chain after selective UV excitation of Anthracene was demonstrated.
Abstract: In the new trichromophoric supermolecule 1, a quantitative intramolecular energy transfer (>98 %) occurs from the anthracene donor to the emitting porphyrin acceptor through the oligothiophene chain after selective UV excitation of anthracene. Energy-transfer properties and fluorescence quantum yields are independent of the oligothiophene chain length. Attachment of further anthrylquinquethienyl chromophores to the porphyrin ring results in an increase in the intensity of characteristic absorption and fluorescence bands.

Journal ArticleDOI
TL;DR: In this article, the cobalt tetramethylporphyrin identified in the title catalyzes the electroreduction of O 2 to H 2 O instead of H2O2.
Abstract: Unlike most simple, monomeric cobalt porphyrins, the cobalt tetramethylporphyrin identified in the title catalyzes the electroreduction of O2 to H2O instead of H2O2. On graphite electrodes, coatings of the porphyrin prepared by irreversible adsorption from chloroform solutions catalyze the electroreduction of O2 in aqueous HClO4 at unusually positive potentials. Both the title porphyrin and the corresponding unsubstituted cobalt porphine are argued to derive their activity as four-electron reduction catalysts from their propensity to form dimers (or higher aggregates) in solution and, presumptively, on the surface of graphite electrodes.

Journal ArticleDOI
TL;DR: In this paper, a cyclophane-type molecular dyads was synthesized by Bingel macrocyclization of porphyrin-tethered bis-malonates 5 or 5.
Abstract: The synthesis of the cyclophane-type molecular dyads 1 and 1 . Zn was accomplished by Bingel macrocyclization of porphyrin-tethered bis-malonates 5 or 5 . Zn, respectively, with C60 (Scheme). In these macrocycles, the doubly bridged porphyrin adopts a close, tangential orientation relative to the surface of the C-sphere. The porphyrin derivatives 6 and 6 . Zn with two appended, singly-linked C60 moieties were also formed as side products in the Bingel macrocyclizations. The trans-1 addition pattern of the fullerene moiety in 1 and 1 . Zn was unambiguously established by 1H- and 13C-NMR spectroscopy. Due to the close spatial relationship between the fullerene and porphyrin components in 1 and 6 and the corresponding ZnII complexes, the porphyrin fluorescence is efficiently quenched as compared to the luminescence emitted by 5 and 5 . Zn, respectively (Fig. 2). Cyclic-voltammetry studies show that the mutual electronic effects exerted by the fullerene on the porphyrin and vice versa in 1 and 1 . Zn are relatively small despite the close proximity between the porphyrin donor and the fullerene acceptor (Fig. 3).

Journal ArticleDOI
TL;DR: In this article, the effect of restricted porphyrin−porphyrin rotation on energy transfer in diphenylethyne-linked porphrin arrays was examined.
Abstract: To examine the effect of restricted porphyrin−porphyrin rotation on energy transfer in diphenylethyne-linked porphyrin arrays, a square macrocyclic array of four porphyrins has been prepared that locks the porphyrins in a mutually coplanar architecture. The palladium-mediated coupling of Zn(II) 5,10-dimesityl-15,20-bis(4-ethynylphenyl)porphyrin and 5,10-dimesityl-15,20-bis(4-iodophenyl)porphyrin afforded the molecular square (cyclo-Zn2Fb2U) with zinc (Zn) and free base (Fb) porphyrins on alternating corners. The yield of cyclo-Zn2Fb2U is relatively insensitive to concentration with reactants at 5−0.5 mM but declines significantly at ≤0.05 mM. Transient absorption data from cyclo-Zn2Fb2U in toluene at room temperature indicate that the rate of energy transfer from the photoexcited Zn porphyrin to a neighboring Fb porphyrin is (26 ps)-1. A ZnFb porphyrin (ZnFbU) with an identical diphenylethyne linker but no constraints on rotation exhibits an identical energy-transfer rate. Resonance Raman spectroscopy sho...

Journal ArticleDOI
TL;DR: Comparison of the equilibrium constant in a zinc chlorin with those of the corresponding zinc bacteriochlorin and porphyrin led to an increase in the saturation and flexibility of the tetrapyrrole pi-plane ligands making the central zinc more axial-ligated.

Journal ArticleDOI
TL;DR: In this paper, heat-treated μ-oxo-iron, tetramethoxy phenyl porphyrin (Fe-TMPP)2O and iron(iii) tetramerethoxy porphrin (FeOEP-Cl) adsorbed on high-area carbons such as deashed and un-deashed RB carbon (Calgon) and Black Pearls-2000 (Cabot) have been found to exhibit stable and very high oxygen reduction rates.
Abstract: Heat-treated μ-oxo-iron(iii) tetramethoxy phenyl porphyrin (Fe-TMPP)2O and iron(iii) tetramethoxy phenyl porphyrin (FeTMPP-Cl) as well as iron(iii) octaethyl porphyrin (FeOEP-Cl) adsorbed on high-area carbons such as deashed and un-deashed RB carbon (Calgon) and Black Pearls-2000 (Cabot) have been found to exhibit stable and very high oxygen reduction rates. Experiments done over a period of 24h showed no performance degradation. Measured performances were very similar to supported platinum (E-Tek), when tested in 85% H3PO4-equilibrated Nafion 117 membrane at 125°C and hydrated-Nafion membrane at 60°C in a minifuel cell. The macrocycle cathodes are insensitive to the presence of methanol whereas the platinum cathodes are very sensitive and show degradation in the oxygen reduction performance.

Journal ArticleDOI
TL;DR: In this paper, the photophysical properties of a series of porphyrin, phthalocyanine, and benzochlorin derivatives were examined for the UV-Vis and fluorescence emission spectra.