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  • 1
    ISSN: 0005-2795
    Keywords: Amino acid substitution ; Hemoglobin variant ; Oxygen affinity ; β-Thalassemia
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0044-2313
    Keywords: Tin complexes ; thiolated ligands ; 119Sn Mössbauer spectra ; molecular dynamics ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zinn(IV)-, Monomethylzinn(IV)- und Dimethylzinn(IV)-Komplexe mit Thiolschwefel- und heterocyclischen Stickstoff-Donatoren: Moleküldynamik und Struktur bei 119Sn-Mössbauer-SpektrenDie Moleküldynamik der Komplexe Sn(SPyN)4 (1), SnCl2(SPyN)2 (2), MeSn(SPy)3 (3), MeSnCl(SPyN)2 (4), Me2Sn(TCy)2 (5), Me2SnCl(TOx) (6) und Me2Sn(TUr) (7) (HSPy = 2-Mercaptopyridin; HSPyN = 2-Mercaptopyrimidin; HTCy = 2-Thiocytosin; HTOx = 8-Thiochinolin; H2TUr = 2-Thiouracil) wurde mit 119Sn-Mössbauer-Spektroskopie bei verschiedenen Temperaturen untersucht. Die Flächen unter den Resonanzlinien wurden als Funktion der Temperatur bestimmt und daraus die Debye-Temperaturen, die cut-off-Frequenzen wie auch die rückstoßfreien Anteile (Lamb-Mössbauer-Faktor) und die mittleren quadratischen Auslenkungen der 119Sn-Atome berechnet. Durch Fingerprintvergleiche auf Grund von Literaturdaten wurden monomere Strukturen den Komplexen (1) bis (4) und (6) zugeordnet, während (5) und (7) an der Grenze monomer eindimensionaler Polymerer liegen. Die Ergebnisse werden auf der Basis bekannter Kristall- und Molekülstrukturen diskutiert. Die Umgebung der Zinnatome wird durch Punktladungsmodell-Berechnungen von Kernquadrupolaufspaltungs-Parametern simuliert; Molekülstrukturen für die Komplexe (5) bis (7), von denen keine Röntgendaten verfügbar sind, werden vorgeschlagen.
    Notes: The molecular dynamics of the complexes Sn(SPyN)4 (1), SnCl2(SPyN)2 (2), MeSn(SPy)3 (3), MeSnCl(SPyN)2 (4), Me2Sn(TCy)2 (5), Me2SnCl(TOx) (6), and Me2Sn(TUr) (7) [HSPy = 2-mercaptopyridine; HSPyN = 2-mercaptopyrimidine; HTCy = 2-thiocytosine; HTOx = 8-thioquinoline; H2TUr = 2-thiouracil] has been investigated by variable temperature 119Sn Mössbauer spectroscopy. The area under the resonant peaks has been determined as function of temperature, from which Debye temperatures and cut-off frequencies, as well as recoil-free fractions (Lamb Mössbauer factor) and mean square displacements of 119Sn, have been calculated. By fingerprint procedures on the basis of literature data, monomeric structures are attributed to complexes (1)-(4) and (6), while (5) and (7) lie in the borderline monomersmonodimensional polymers. The results are discussed on the basis of known crystal and molecular structures. The nature of the environment of tin atoms has been simulated by point-charge model calculations of nuclear quadrupole splitting parameters; molecular structures are proposed for complexes (5)-(7), where no X-ray diffractometric data are available.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0268-2605
    Keywords: organotin(IV) ; porphine ; Mössbauer ; NMR ; development ; Ascidiaceae ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Diorgano- and triorgano-tin(IV) derivatives of meso-tetra(4-sulfonatophenyl)porphine (H4TPPS) with general formula (R2Sn)2TPPS and (R3Sn)4TPPS (TPPS4-=[meso-tetra(4-sulfonatophenyl)porphinate]4-, R=Me, Bu, Ph) have been obtained and their solid-state configuration inferred on the basis of IR and Mössbauer spectroscopy, while solution-phase studies have been carried out by 1H and 13C NMR in DMSO-d6, together with determination of the in vivo cytotoxicity of the new derivatives towards embryonic development of Ciona intestinalis. In particular, octahedral and trigonal-bipyramidal eq-R3Sn polymeric configurations are proposed, in the solid state, respectively for (R2Sn)2TPPS and (R3Sn)4TPPS complexes, with the arylsulfonate groups behaving as monoanionic bidentate bridging ligands.The 1H and 13C NMR data lead to the conclusion that the metal-to-ligand ratio (2:1 or 4:1), binding site (the sulfonato-group oxygens), and the coordination polyhedron around the metal (trans-octahedral or trigonal-bipyramidal) found in the solid state are preserved in solution. © 1997 John Wiley & Sons, Ltd.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
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