Search results for "PORP"
showing 10 items of 567 documents
Regioselective C–H amination of free base porphyrins via electrogenerated pyridinium-porphyrins and stabilization of easily oxidized amino-porphyrins…
2020
Four free base aminoporphyrins were synthesized in two steps via regioselective anodic nucleophilic substitution with pyridine followed by ring opening of the electrogenerated pyridinium with piperidine. The X-ray crystallographic structure of the unstable 2-aminotetraphenylporphyrin was solved. Protonation of this latter compound leads to the stable diiminium porphyrin salt.
Chemically induced chromosome damage in early-developing embryos ofAnilocra physodes L. (Crustacea, Isopoda) following exposure to bis[Dimethyltin(IV…
1993
In order to obtain chromosome preparations from early-developing embryos of Anilocra physodes, a squash technique has been successfully employed. Results gathered after exposure of this material to bis[dimethyltin(IV)chloro]protoporphyrin IX {[(CH3)2SnCl]2 - Protoporphyrin IX} solutions at different exposure times suggest that this chemical complex is capable of producing abnormal metaphase and anaphase figures in proportion to its concentration and not to exposure length. Essentially, all of the chromosome abnormalities are classifiable as chromosome fragments mainly observed at the metaphase stage; chromosome bridges; and large decondensed chromosome regions.
Organometallic complexes with biological molecules. I. Diorganotin(IV)chloro protoporphyrin IX complexes: Solid-state and solution-phase characteriza…
1993
Protoporphyrin IX (H4PPIX) complexes of diorganotin(IV)chloro moieties with formula (R2SnCl)2H2PPIX (RMe, Bu and Ph) have been obtained and their solid-state and solution-phase configurations have been studied through spectroscopic investigations. Coordination of the side-chain carboxylates of H4PPIX to R2Sn(IV)Cl moieties, with bridging carboxylate (COO−) has been inferred by comparison of the free and coordinated H4PPIX IR spectra, while the occurrence of a five-coordinated tin(IV) atom in a cis-R2 trigonal bipyramidal structure has been deduced, for all of the synthesized complexes, by rationalization of the nuclear quadrupole splitting parameters, according to the point-charge model for…
ChemInform Abstract: Chemically Induced Chromosome Damage in Early-Developing Embryos of Anilocra Physodes L. (Crustacea, Isopoda) Following Exposure…
2010
In order to obtain chromosome preparations from early-developing embryos of Anilocra physodes, a squash technique has been successfully employed. Results gathered after exposure of this material to bis[dimethyltin(IV)chloro]protoporphyrin IX {[(CH3)2SnCl]2 - Protoporphyrin IX} solutions at different exposure times suggest that this chemical complex is capable of producing abnormal metaphase and anaphase figures in proportion to its concentration and not to exposure length. Essentially, all of the chromosome abnormalities are classifiable as chromosome fragments mainly observed at the metaphase stage; chromosome bridges; and large decondensed chromosome regions.
Computational study of dimethyl- and trimethyl-tin(IV) complexes of porphyrin derivatives
2001
The molecular geometry, energetics and electronic charge distribution of diorgano- and triorgano-tin(IV) complexes of [protoporphyrin-IX] and [meso-tetra(4-carboxyphenyl)porphine] derivatives were determined at semi-empirical and ab initio levels. To study the molecular details of the complexes, simpler molecule models were calculated by the ab initio pseudo-potential method. The molecular properties of these complexes are essentially independent of the presence of the peripheral tin atoms. Agreement was always found among the results of the different computational approaches, as well as between the theoretical and the experimental findings on the molecular geometry of the hypothesized comp…
Positive Allosteric Control of Guests Encapsulation by Metal Binding to Covalent Porphyrin Cages
2018
The allosteric control of the receptor properties of two flexible covalent cages is reported. These receptors consist of two zinc(II) porphyrins connected by four linkers of two different sizes, each incorporating two 1,2,3‐triazolyl ligands. Silver(I) ions act as effectors, responsible for an on/off encapsulation mechanism of neutral guest molecules. Binding silver(I) ions to the triazoles opens the cages and triggers the coordination of pyrazine or the encapsulation of N,N′‐dibutyl‐1,4,5,8‐naphthalene diimide. The X‐ray structure of the silver(I)‐complexed receptor with short connectors is reported, revealing the hollow structure with a cavity well‐defined by two eclipsed porphyrins. Rath…
Molecular Mechanisms Leading from Periodontal Disease to Cancer
2022
Periodontitis is prevalent in half of the adult population and raises critical health concerns as it has been recently associated with an increased risk of cancer. While information about the topic remains somewhat scarce, a deeper understanding of the underlying mechanistic pathways promoting neoplasia in periodontitis patients is of fundamental importance. This manuscript presents the literature as well as a panel of tables and figures on the molecular mechanisms of Porphyromonas gingivalis and Fusobacterium nucleatum, two main oral pathogens in periodontitis pathology, involved in instigating tumorigenesis. We also present evidence for potential links between the RANKL–RANK signaling axi…
Mössbauer investigations of the hexachlorantimonate salt of the phenyliron 2,3,7,8,l2,13,17,18-octaethyl-5,10,15,20-tetraphenylporphyrinate, [Fe(oetp…
2002
Abstract The phenyliron derivative, [Fe(oetpp)C6H5)]SbCl6 (2) generated in dichloromethane by oxidation of the phenyliron(III) complex, Fe(III) (oetpp)C6H5 (1) of the 2,3,7,8,12,13,17,18-octaethyl-5,10,15,20-tetraphenylporphyrin with 1 equiv. of phenoxathiinylium hexachloroantimonate, [C12H8OS]SbCl6, was studied by Mossbauer spectroscopy. This compound exhibits an isomer shift δ of 0.13 mm s−1 and a quadrupole splitting ΔEQ of 3.23 mm s−1. The measured magnetic hyperfine pattern obtained in the temperature range 4.2–40 K in a field of 3.5 and 7 T, applied perpendicular to the γ-beam, has been consistently analyzed in the spin Hamiltonian approximation assuming an iron(IV) S=1 electronic con…
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…
Persistent electron-transfer state of a pi-complex of acridinium ion inserted between porphyrin rings of cofacial bisporphyrins
2006
A free-base cofacial bisporphyrin, H(4)DPOx, forms a pi-complex with acridinium ion (AcH(+)) by pi-pi interaction in benzonitrile (PhCN). Formation of the H(4)DPOx-AcH(+) pi-complex was probed by UV-vis and NMR spectroscopy. The binding constant between AcH(+) and H(4)DPOx is determined as 9.7 x 10(4) M(-)(1). Photoinduced electron transfer (ET) from the H(4)DPOx to the AcH(+) moiety occurred efficiently in the pi-complex to form the ET state (H(4)DPOx(*)(+)-AcH(*)). The ET state is successfully detected by laser flash photolysis. The lifetime of the ET state is 18 mus in PhCN at 298 K, and the quantum yield of the ET state is 90%. The temperature dependence of the ET state lifetime has bee…