Search results for "Porphyrins"

Photocatalytic degradation of 4-nitrophenol in aqueous suspension by Using Functionalized Porphyrin-TiO2 Photocatalysis Under Visible Irradiation

2007

Functionally relevant electric-field induced perturbations of the prosthetic group of yeast ferrocytochrome c mutants obtained from a vibronic analys…

2006

We have measured the low temperature (T = 20 K) absorption spectra of the N52A, N52V, N52I, Y67F, and N52AY67F mutants of ferrous Saccharomyces cerevisiae (baker's yeast) cytochrome c. All the bands in the Q0- and Q(v)-band region are split, and the intensity distributions among the split bands are highly asymmetric. The spectra were analyzed by a decomposition into Voigtian profiles. The spectral parameters thus obtained were further analyzed in terms of the vibronic coupling model of Schweitzer-Stenner and Bigman (Schweitzer-Stenner, R.; Bigman, D. J. Phys. Chem. B 2001, 7064-7073) to identify parameters related to electronic and vibronic perturbations of the heme macrocycle. We report th…

Adducts of free-base meso-tetraarylporphyrins with trihaloacetic acids: Structure and photostability

2020

Abstract Four diverse meso-tetraarylporphyrins in the form of diprotonated adducts with trifluoro-, trichloro-, tribromoacetic acids and acetic acid were investigated in benzene solution. Despite similar structural distortion of the chromophore system due to protonation, the respective adducts demonstrated different photostability when exposed to UV irradiation. The trifluoro- and trichloroacetic adducts, and the acetic acid one, showed some common features both molecular and in the mechanism of photodegradation. However, the tribromo-derivative decayed according to a different kinetic scheme, revealing a considerable impact of the bromine atoms upon the pyrrole units of the porphyrin macro…

Ruthenium(II) meso-tetra-(benzo-15-crown-5)-porphyrinates: synthesis and spectroscopic investigation

2007

The synthesis of novel ruthenium(II) meso-tetra-(benzo-15-crown-5)-porphyrinates, meso-[( B 15 C 5)4 Por ] Ru ( CO )( MeOH ) (1) and meso-[( B 15 C 5)4 Por ] Ru ( L )2 (2)-(4) (meso-[( B 15 C 5)4 Por ]2-= 5,10,15,20-tetrakis-(benzo-15-crown-5)-porphyrinato-dianion; L = pyridine (py), pyrazine (pyz), 4,4′-bipyridyl (4,4′-bpy)), where CO and MeOH , or two N -donor ligands are axially coordinated to the central metal, are reported. The metalation of the free ligand performed by the reaction of Ru 3( CO )12 with meso-[( B 15 C 5)4 Por ] H 2 in 1,2,4-trichlorobenzene (TCB, bp = 215°C), gives (1) in a high yield. The synthesis of (2)-(4) involves the decarbonylation of (1) with trimethylamine N …

Spectral hole burning study of protoporphyrin IX substituted myoglobin.

1992

Protoporphyrin IX substituted myoglobin reveals excellent hole burning properties. We investigated the frequency shift of persistent spectral holes under isotropic pressure conditions in a range from 0 to 2.4 MPa. In this range, the protein behaves like an elastic solid. The shift of the holes under pressure shows a remarkable frequency dependence from which the compressibility of the protein can be determined. The compressibility, in turn, allows for an estimation of the equilibrium volume fluctuations. Within the frame of the model used to interpret the pressure data, it is possible to determine the absorption frequency of the isolated chromophore and the associated solvent shift in the p…

Influence of Pendant Arms Bearing Ligating Groups on the Structure of Bismuth Porphyrins: Implications for Labeling Immunoglobulins Used in Medical A…

2004

International audience; The synthesis of two picket bismuth(III) porphyrins is reported, and their crystal structures are compared. The influence of the nature of the pickets, as well as their number, is discussed in terms of stability, kinetics of metalation, structure, and distortion of the porphyrin. Unexpectedly, the resultsindicate that the coordination sphere of bismuth is not affected by different types of distortion nor is the stability of the complex. For both types of complexes, the X-ray crystallography revealed that a single arm is actually in direct interaction with the bismuth cation, thereby allowing furtherfunctionalization on the porphyrin core as the linkage with immunoglo…

Diorganotin(IV) and triorganotin(IV) complexes of meso-tetra(4-sulfonatophenyl) porphine induce apoptosis in A375 human melanoma cells

2006

The cytotoxic effect of several diorganotin(IV) and triorganotin(IV)-meso-tetra(4-sulfonatophenyl)porphine derivatives was tested and only the (Bu(2)Sn)(2)TPPS and the (Bu(3)Sn)(4)TPPS showed cytotoxicity on A375 human melanoma cells. To examine the pathway of (Bu(2)Sn)(2)TPPS or (Bu(3)Sn)(4)TPPS induced A375 cell death, DNA fragmentation analysis, Annexin V binding and PI uptake as well as caspases activation analysis by Western blot were carried out. A375 cells treated exhibited several typical characteristics of apoptosis. Both the (Bu(2)Sn)(2)TPPS and the (Bu(3)Sn)(4)TPPS compounds activate caspase-8 and caspase-9 leading to caspase-3 activation. Thus, we propose that these two porphiri…

Clarification of the oxidation state of cobalt corroles inheterogeneous and homogeneous catalytic reduction of dioxygen

2008

Co(III) corroles were investigated as efficient catalysts for the reduction of dioxygen in the presence of perchloric acid in both heterogeneous and homogeneous systems. The investigated compounds are (5,10,15-tris(pentafluorophenyl)corrole)cobalt (TPFCor)Co, (10-pentafluorophenyl-5,15-dimesitylcorrole)cobalt (F 5PhMes 2Cor)Co, and (5,10,15-trismesitylcorrole)cobalt (Mes 3Cor)Co, all of which contain bulky substituents at the three meso positions of the corrole macrocycle. Cyclic voltammetry and rotating ring-disk electrode voltammetry were used to examine the catalytic activity of the compounds when adsorbed on the surface of a graphite electrode in the presence of 1.0 M perchloric acid, a…

Effect of agricultural practices on soil microbial communities

2008

Soil carbon sequestration is an important and immediate sink for removing atmospheric carbon dioxide and slowing global warming. Agricultural practices strongly impact CO2 emission from the soil and the loss of soil organic matter is lower when “no-till” agriculture is practiced. The present work was performed in order to investigate effects of different agricultural practices on soil microbial communities. Field experiments took place at three Italian locations strongly differing in pedological, chemical and climatic characteristics: Naples, Turin and Piacenza. Soils were subjected to four management practices such as traditional (TRA), minimum tillage (MIN) and amendments with compost (CO…

Exploring the redox reactivity of magnesium porphine. Insight into the origins of electropolymerisation.

2010

International audience; Magnesium(II) porphine, MgP (1), was synthesised according to the Lindsey procedure allowing to isolate and crystallise 1-formyldipyrromethane (2) as a synthetic intermediate. Unprecedented Xray diffraction studies revealed multiple intermolecular associations in the crystal between neighbouring units of 2, namely hydrogen bond and CH … π. The electrochemical behaviour of 1 was examined by means of cyclic voltammetry. In oxydation, two well-defined and distinct steps are assigned to macrocycle concerned electron transfers yielding initially the π-cation radical and π dication, respectively. The highly reactive dication condenses neutral magnesium porphine to form a d…