Search results for " Mossbauer"
showing 10 items of 30 documents
Coordination properties of adenosine-5'-monophosphate and related ligands towards Me2Sn(IV)2+ in aqueous solution.
2002
Abstract The coordination of Me 2 Sn(IV) 2+ to adenosine-5′-monophosphate (AMP) and the related compounds d -ribose-5-phosphate (R5P), d -glucose-1-phosphate (G1P) and d -glucose-6-phosphate (G6P) in aqueous solution was investigated by means of potentiometric titration, and 1 H-, 31 P-NMR and Mossbauer spectroscopic methods in the pH range 2–11 ( I =0.1 M NaClO 4 , 298 K). The complex of AMP and Me 2 Sn(IV) 2+ precipitated at low pH was characterised by elemental analysis, FT-IR and Mossbauer spectroscopic methods. From a comparison of the p K values obtained in the presence and absence of metal ion and the stability constants for the different systems, the coordination of {N} is excluded,…
The dynamics of 57Fe nuclei in Fe(II)-DNA and [Fe(II)(1-methyl-2-mercaptoimidazole)2]-DNA condensates.
2002
Abstract Alcoholic solutions of FeCl 2 and Fe II (Hmmi) 2 Cl 2 (Hmmi=1-methyl-2-mercaptoimidazole) induce calf thymus DNA condensation from aqueous solutions buffered at pH 7.4. A 1:1 Fe II –(DNA monomer) stoichiometry is assumed. The 57 Fe Mossbauer hyperfine parameters suggest an octahedral coordination environment, severely distorted, in both Fe II –(DNA monomer) and [Fe II (Hmmi) 2 ]–(DNA monomer) condensates. The dynamic properties of iron nuclei in freeze-dried samples were investigated by means of variable temperature 57 Fe Mossbauer spectroscopy. Mean square displacements, 〈 x 2 〉( T ), were calculated, such as the effective vibrating mass and the Mossbauer lattice temperature of th…
Synthesis, structural investigations on organotin(IV) chlorin-e6 complexes, their effect on sea urchin embryonic development and induced apoptosis
2004
Four new organotin(IV) chlorin derivatives, [chlorin=chlorin-e(6)=21H,23H-porphine-2-propanoic acid, 18-carboxy-20-(carboxymethyl)-8-ethenyl-13-ethyl-2,3-di-hydro-3,7,12,17-tetramethyl-(2S-trans)-], with formula (R(2)Sn)(3)(chlorin)(2).2H(2)O (R=Me, n-Bu) and (R(3)Sn)(3)chlorin.2H(2)O (R=Me, Ph) have been synthesized. The solid state and solution phase structures have been investigated by FT-IR, (119)Sn Mössbauer, (1)H and (13)C NMR spectroscopy. In the solid state, (R(2)Sn)(3)(chlorin)(2).2H(2)O complexes contain six coordinated Sn(IV), in a skew trapezoidal environment by forming trans-R(2)SnO(4) polymeric units. As far as (R(3)Sn)(3)chlorin.2H(2)O complexes are concerned, Sn(IV) is five …
Synthesis and characterization of Sn(IV) complexes of lower rim 1,3-diacid derivative of calix[4]arene and their protective effects on tissue oxidati…
2005
The two Sn(IV) complexes synthesized using calix[4]arene-1,3-di-acid derivative were characterized by analytical, 1H, 13C and 119Sn NMR, matrix assisted laser desorption ionization mass, and 119Sn Mossbauer techniques and found that the complexes are tetranuclear possessing structurally two different types of tin centers. These complexes were evaluated for their protective value against blood and tissue oxidative stress in lead exposed male albino rats of Wistar strain. The results suggest that the two tin complexes significantly protect changes in lead induced biochemical variables indicative of heme synthesis pathway and exhibit only moderate effect on tissue oxidative stress. The benefic…
Towards a revisitation of vesuvianite-group nomenclature: the crystal structure of Ti-rich vesuvianite from Alchuri, Shigar Valley
2016
Vesuvianite containing 5.85 wt% TiO2from an Alpine-cleft-type assemblage outcropped near Alchuri, Shigar Valley, Northern Areas, has been investigated by means of electron microprobe analyses, gas-chromatographic analysis of H2O, X-ray powder diffraction, single-crystal X-ray structure refinement,27Al NMR,57Fe Mössbauer spectroscopy, IR spectroscopy and optical measurements. Tetragonal unit-cell parameters are:a= 15.5326 (2),c= 11.8040 (2) Å, space groupP4/nnc. The structure was refined to finalR1= 0.031,wR2= 0.057 for 11247I> 2σ(I). A general crystal-chemical formula of studied sample can be written as follows (Z= 2):[8–9](Ca17.1Na0.9)[8]Ca1.0[5](Fe2+0.44Fe3+0.34Mg0.22)[6](Al3.59Mg0.41)…
Characterization of complexes formed between [Me2Sn(IV)]2+ and carboxymethylcelluloses.
2006
Complexes formed between carboxymethylcellulose (CMC) and the [Me(2)Sn(IV)]2+ cation have been prepared in the solid state and characterized by FTIR and Mossbauer spectroscopy. The complexes contained CMC with varying molar weight and degree of carboxylation, and the complexes were isolated both from acidic and from neutral solutions at varying metal-to-ligand ratios. The characteristic vibration bands of the ligands were identified from their pH-dependent FTIR spectra. In the organotin(IV) complexes obtained at pH approximately 2, the -COO- moieties were found to be coordinated in a monodentate manner, and the band characteristic of the protonated (unbound) -COO- group(s) was also identifi…
Hemoglobin dynamics in rat erythrocytes investigated by M�ssbauer spectroscopy
1991
Rats have been enriched in 57Fe and erythrocytes were isolated from the blood. Mössbauer absorption spectroscopy on the hemoglobin of these erythrocytes has shown rather similar dynamics as found earlier in crystals of myoglobin, in frozen solutions of human hemoglobin and in a number of other proteins. The results strongly indicate that the motion of the heme and presumably some part of the F-helix is mainly influenced by the average viscosity of the sample determined by a network of hydrogen bridges and other weak interactions. Extrapolations of Mössbauer results from protein crystals to proteins in their physiological surroundings seem to be suitable for heme proteins.
Equilibrium, Structural and Biological Activity Studies on [Organotin(IV)]n+ Complexes
2008
Organotin(IV) compounds are characterized by the presence of at least one covalent C–Sn bond. The compounds contain tetravalent {Sn} centers and are classified as mono-, di-, tri-, and tetraorganotin(IV), depending on the number of alkyl (R) or aryl (Ar) moieties bound. The anions are usually Cl, F, O2, OH,–COO, or –S. It seems that the nature of the anionic group has only secondary importance in biological activity. The rapid rise in the industrial (catalyst in PVC and foam production), agricultural (fungicides and acaricides), and biological applications (wood, stone, and glass preservatives) of organotin(IV) compounds during the last few decades has led to their accumulation in the envir…
Basaltic Rocks Analyzed by the Spirit Rover in Gusev Crater
2004
The Spirit landing site in Gusev Crater on Mars contains dark, fine-grained, vesicular rocks interpreted as lavas. Pancam and MiniâThermal Emission Spectrometer (Mini-TES) spectra suggest that all of these rocks are similar but have variable coatings and dust mantles. Magnified images of brushed and abraded rock surfaces show alteration rinds and veins. Rock interiors contain â¤25% megacrysts. Chemical analyses of rocks by the Alpha Particle X-ray Spectrometer are consistent with picritic basalts, containing normative olivine, pyroxenes, plagioclase, and accessory FeTi oxides. MoÌssbauer, Pancam, and Mini-TES spectra confirm the presence of olivine, magnetite, and probably pyroxene. The…
Mineralogy at Gusev Crater from the Mössbauer spectrometer on the Spirit Rover.
2004
Mössbauer spectra measured on Mars by the Spirit rover during the primary mission are characterized by two ferrous iron doublets (olivine and probably pyroxene) and a ferric iron doublet (tentatively associated to nanophase ferric iron oxide). Two sextets resulting from nonstoichiometric magnetite are also present, except for a coating on the rock Mazatzal, where a hematite-like sextet is present. Greater proportions of ferric-bearing phases are associated with undisturbed soils and rock surfaces as compared to fresh rock surfaces exposed by grinding. The ubiquitous presence of olivine in soil suggests that physical rather than chemical weathering processes currently dominate at Gusev crat…