Search results for "MÖSSBAUER SPECTROSCOPY"
showing 10 items of 364 documents
Synthesis and characterization of some diorganotin(IV) complexes of Schiff bases derived from a non-protein amino acid. Crystal structures of {HO2CC6…
2008
Diorganotin(IV) complexes R2Sn(LH)2 (R = Me, nBu) and {[nBu2Sn(LH)]2O}2 (LH = 4-[(2Z)-(3-hydroxy-1-methyl-2-butenylidene)amino]benzoate and 4-[{(E)-1-(2-hydroxyphenyl)methylidene}mino]benzoate) have been reported. The complexes were characterized by elemental analysis, IR, NMR (1H, 13C, 119Sn) and 119mSn Mossbauer spectroscopy. Crystal structures of a ligand {HO2CC6H4[NC(H)}{C(CH3)CH(CH3)-3-OH]-p} and one of its di-n-butyltin(IV) complexes (nBu2Sn{O2CC6H4[NC(H)}{C(CH3)CH(CH3)-3-OH]-p}2) were determined. The spectroscopic data suggest that R2Sn(LH)2 complexes have skew-trapezoidal bipyramidal structure while {[nBu2Sn(LH)]2O}2 complexes adopt a dimeric tetraorganodistannoxane structure in the…
Field-portable Mössbauer spectroscopy on Earth, the Moon, Mars, and beyond
2011
ABSTRACT Iron occurs naturally as Fe 2+ , Fe 3+ , and, to a lesser extent, as Fe 0 . Many fundamental (bio)geochemical processes are based on redox cycling between these oxidation states. Mossbauer spectroscopy provides quantitative information about the distribution of Fe among its oxidation states, identification of Fe-bearing phases, and relative distribution of Fe among those phases. Portable, miniaturised Mossbauer spectrometers were developed for NASA9s Mars Exploration Rovers (in operation since 2004) and provide a means for non-destructive, in-situ field investigations. On Mars, these instruments provided evidence for aqueous activity with implications for habitability, were applied…
Thermal and pressure-induced spin crossover in a novel three-dimensional Hoffman-like clathrate complex
2011
The synthesis and crystal structure of the interpenetrated metal–organic framework material Fe(bpac)2[Ag(CN)2]2 (bpac = 4,4′-bis(pyridyl)acetylene) are reported along with the characterization of its spin crossover properties by variable temperature magnetometry and Mossbauer spectroscopy. The complex presents an incomplete stepped spin transition as a function of temperature that is modified upon successive thermal cycling. The pressure-induced transition has also been investigated by means of high pressure Raman spectroscopy using a diamond anvil cell. The results show that it is possible to reach the thermally-inaccessible fully low spin state at room temperature by applying hydrostatic …
A spin transition molecular material with a wide bistability domain.
2002
International audience; [Fe(hyptrz)3](4-chloro-3-nitrophenylsulfonate)22 H2O (1; hyptrz=4-(3-hydroxypropyl)-1,2,4-triazole) has been synthesized and its physical properties have been investigated by several physical techniques including magnetic susceptibility measurements, calorimetry, and Mössbauer, optical, and EXAFS spectroscopy. Compound 1 exhibits a spin transition below room temperature, together with a very wide thermal hysteresis of about 50 K. This represents the widest hysteresis loop ever observed for an FeII-1,2,4-triazole spin transition material. The cooperativity is discussed on the basis of temperature-dependent EXAFS studies and of the structural features of a CuII analogu…
The photocycle and the structure of iron containing bacteriorhodopsin ?a kinetic and M�ssbauer spectroscopy investigation
1990
Bacteriorhodopsin (bR), converted by deionization to the blue form was reconstituted to the active purple membrane by the addition of Fe2+ or Fe3+ ions. 57Fe Mossbauer spectra of these samples were measured at different pH values (pH 3.9, pH 5.0 and pH 7.0) and at temperatures ranging from 4 K to 300 K. The hyperfine parameters reveal two iron environments with oxygen atoms in the neighbourhood of iron. Iron type 1 is in the 3+ high spin state. It is bound to acid side chains of the protein and/or the phosphate groups of the lipids. Iron type 2 is in the 2+ high spin state and is linked to carboxy groups of the protein in a rather unspecific way. Dynamics as measured by Mossbauer spectrosco…
Synthesis, chemical characterization and biological activity of new histone acetylation/deacetylation specific inhibitors: a novel and potential appr…
2013
Three new triorganotin(IV) complexes of valproic acid (vp1, Me3Sn-valproate; vp2, Bu3Sn-valproate; vp3, Ph3Sn-valproate) have been synthesized and investigated by spectroscopic and biological methods. An anionic, monodentate valproate ligand was observed, ester-like coordinating the tin atom on a tetra-coordinated, monomeric environment. The structures, though, can distort towards a penta-coordination, as a consequence of a long range O center dot center dot center dot Sn interaction. Crystallographic and NMR findings confirm this situation both in solid state and solution. Biological finding evidenced a clear cytotoxic action of the complexes in hepatocellular carcinoma cell cultures: one …
Syntheses and Solid-State Structures of Some Dialkyltin Derivatives of ?-Methoxy- and ?-Acetoxy-phenylacetic Acids
1996
Several di-n-butyltin and diethyltin biscarboxylates and distannoxanes of α-methoxy- and α-acetoxy-phenylacetic acids were synthesized and (two of) their structures were studied by means of X-ray diffraction analysis as well as by means of IR and Mossbauer spectroscopies. It was shown for {[(n-Bu) 2 - SnOC(O)CH(OMe)Ph] 2 O} 2 that there is an interaction between the OMe group and one of the endocyclic tin atoms, resulting in a distorted pentagonal-bipyramidal geometry with the pentagonal plane defined by five O atoms and an uncommon seven coordination number for this tin atom. Spectral data indicate that biscarboxylates have trans-octahedral structures.
Synthesis of polymeric alkoxides from dialkyltin(IV) oxides and chloral, and their characterization by mössbauer and infrared spectroscopy
1979
Abstract The reaction of (Alk2SnO)n with OCH·CCl3 gives compounds of elemental formula Alk2SnOCH- (CCI3)O (Alk = Bun, Octn), probably by addition of the Sn-O bond to the carbonyl group. Mossbauer parameters suggest the occurrence of five-coordinated Sn, and polymeric structures with bridging three- coordinating oxygens are proposed. The assumption that C2SnO3 units with trigonal bipyramidal type structures are present is consistent with point-charge model rationalization of the quadrupole splitting. Infrared spectra are in keeping with the proposed structures, suggesting, inter alia, bent C Sn C skeletons, but the analysis of possible ν(Sn-O) modes does not provide conclusive evidence for t…
[Fe(TPT)(2/3){M(I)(CN)2}2]⋅nSolv (M(I) = Ag, Au): new bimetallic porous coordination polymers with spin-crossover properties.
2013
Two new heterobimetallic porous coordination polymers with the formula [Fe(TPT)2/3{MI(CN)2}2]¿nSolv (TPT=[(2,4,6-tris(4-pyridyl)-1,3,5-triazine]; MI=Ag (nSolv=0, 1¿MeOH, 2¿CH2Cl2), Au (nSolv=0, 2¿CH2Cl2)) have been synthesized and their crystal structures were determined at 120¿K and 293¿K by single-crystal X-ray analysis. These structures crystallized in the trigonal R-3m space group. The FeII ion resides at an inversion centre that defines a [FeN6] coordination core. Four dicyanometallate groups coordinate at the equatorial positions, whilst the axial positions are occupied by the TPT ligand. Each TPT ligand is centred in a ternary axis and bridges three crystallographically equivalent Fe…
Diphenyltin(IV) complexes of the 5-[(E)-2-(aryl)-1-diazenyl]quinolin-8-olates: Synthesis and multinuclear NMR, 119Sn Mössbauer, electrospray ionizati…
2006
Abstract A series of cis-bis{5-[(E)-2-(aryl)-1-diazenyl]quinolinolato}diphenyltin(IV) complexes have been synthesized and characterized by 1H, 13C, 119Sn NMR, ESI-MS, IR and 119mSn Mossbauer spectroscopic techniques in combination with elemental analysis. The structures of a ligand L6H (i.e., 5-[(E)-2-(4-ethoxyphenyl)-1-diazenyl]quinolin-8-ol) and three diphenyltin(IV) complexes, viz., Ph2Sn(L1)2 · (CH3)2CO (1), Ph2Sn(L4)2 (4) and Ph2Sn(L5)2 (5) (L = 5-[(E)-2-(aryl)-1-diazenyl]quinolin-8-ol: aryl = phenyl – (L1H); 4′-methylphenyl – (L4H) and 4′-bromophenyl – (L5H)) were determined by single crystal X-ray diffraction. In general, the complexes were found to adopt a distorted cis-octahedral a…