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  • 1
    Electronic Resource
    Electronic Resource
    The interaction of organotins with native DNA (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 6 (1992), S. 537-542 
    Details
    ISSN: 0268-2605
    Keywords: Organotin ; DNA ; Mössbauer ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The compounds R2SnCl2 and R3SnCl (R=Me, Et, nBu, nOct, Ph, in ethanol solution) as well as the aqueous species [Me2Sn(OH2)n]2+ and [Me3Sn(OH2)2]+, react with aqueous native DNA, yielding solid phases. According to the pointcharge model treatment of the 119Sn Mössbauer parameter nuclear quadrupole splitting, trans-octahedral R2Sn(O2PXY)2, and trigonalbipyramidal R3Sn(O2PXY), (R=Me, Et, nBu), would occur in the pellets, the tin atoms being coordinated by phosphodiester groups of the nucleic acid. The precipitates from Ph2SnIV would consist of the DNA complex as well as of the Ph2SnIV distannoxane obtained by hydrolysis of the reactant, whilst nOct2SnCl2, nOct3SnCl and Ph3SnCl would mainly yield stannoxanes and hydroxides. The water-soluble hydrolyzed species [Me2Sn(OH)(OH2)n]+, Me2Sn(OH)2 and Me3Sn(OH)(OH2) do not show any interaction with native DNA, although they are possibly coordinated by phosphate oxygen atoms in model aqueous systems, in the presence of excess ligand.These trends have been rationalized by QSAR approach (Quantitative Structure-Activity Relationships) in terms of electronic factors related to tin-oxygen (phosphate) Coulomb interactions, as well as the lipophilicity of R in the RnSnIV moieties.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aoc.590060611
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  • 2
    Electronic Resource
    Electronic Resource
    119Sn Mössbauer studies of bis[cysteinato(1-)-S]- and bis[penicillaminato(1-)-S]-diorganotin(IV) species in the crystalline state and in frozen aqueous solution (1988)
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 2 (1988), S. 525-531 
    Details
    ISSN: 0268-2605
    Keywords: organotin ; amino-acid ; cysteine ; penicillamine ; Mössbauer ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The bonding and the configuration of the tin environment in the title compounds {R2Sn[SCH2CH(NH3+)COO-]2 and R2Sn[SC(CH3)2CH(NH3+)COO-]2, indicated in the following as R2Sn(cysH)2 and R2Sn(penH)2 respectively} has been investigated through the determination of the Mössbauer-Zeeman spectra of Ph2Sn(cysH)2 and Ph2Sn(penH)2 in the solid state, and through conventional Mössbauer spectroscopy of Me2Sn(penH)2 in the solid state as well as of Me2Sn(cysH)2 and Me2Sn(penH)2 in aqueous solution (frozen). The treatment of the data by the pointcharge model approach suggested the general occurrence of a tetrahedral C2SnS2 core. In aqueous Hepes buffer, a tertiary amino nitrogen atom has been observed to coordinate tin in Me2Sn(cysH)2 and Me2Sn(penH)2, with formation of trigonal bipyramidal tin environments. The latter solutions undergo slow decomposition reactions at room temperature. From (Me2SnS)3 occurs, as well as formation of soluble complex species in the presence of glycylglycine; Me2Sn(penH)2 appears to undergo a slow desulfuration reaction.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aoc.590020605
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  • 3
    Electronic Resource
    Electronic Resource
    A study of dimethyltin(IV)-L-cysteinate in aqueous solution (1988)
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 2 (1988), S. 417-425 
    Details
    ISSN: 0268-2605
    Keywords: organotin ; cysteinate ; murine P-388 leukaemia ; infrared spectra ; NMR spectra ; Mössbauer spectra ; structures ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The in vivo activity of some R2Sn-L-cysteinate complexes (R = Me, Et, n-Bu) against murine P-388 leukaemia has been tested. Only the Et2Sn(IV) complex showed a marginal positive effect. Trigonal bipyramidal tin environments with two carbon (R) atoms and the sulfur atom in the equatorial plane and oxygen (carboxylate) and nitrogen (NH2) in apical positions have been proposed for the solid compexes (R = Me, Et, n-Bu, Ph) on the basis of experimental Mössbauer parameters and infrared (IR) data. Aqueous solutions of the Me2Sn—L-cysteinate have been studied by IR, 1H NMR and 119Sn Mössbauer spectroscopy (in frozen solution) at different pH values to identify the Me2Sn(IV) species present. At pH 〉 2 the dimethyltin aquocation is complexed by the ionized sulfhydryl group of L-cysteine to form a five-coordinated species. With increasing pH values, NH3+ is deprotonated and a chelate is proposed with both the sulfhydryl and the amino group bonded to tin, one water molecule or (at still higher pH values) one hydroxyl ion occupying the fifth coordination site of a trigonal bipyramid around tin. Finally at pH 〉 10 the NH2 group is substituted by a hydroxyl ion.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aoc.590020503
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  • 4
    Electronic Resource
    Electronic Resource
    Interactions of organotins with biological systems (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 6 (1992), S. 127-138 
    Details
    ISSN: 0268-2605
    Keywords: Organotin ; biological molecules ; Mössbauer ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The bonding and structure in the environments of tin atoms in organotin-biological molecules has been investigated by 119Sn Mössbauer spectroscopy, mainly through the rationalization of the nuclear quadrupole splitting parameter by pointcharge model approaches.Organotin moieties R2SnIV and R3SnIV (R = Me, nBu, Ph) generally assume trigonal-bipyramidal type configurations in membranes of human erythrocytes, when incubated with whole erythrocytes and erythrocyte ghosts at the level of micromolar (μmol dm-3) organotin per mg of membrane protein. Corresponding structures are assumed by Me2SnIV and Me3SnIV in the cytoplasm. Ethanolic Me2SnCl2 yielded distorted trans-octahedral species when reacted with ghost cells. These configurations may in principle originate through coordination of the metal by donor nitrogen or oxygen atoms from the cell constituents, such as protein side chains and related component molecules, carbohydrate fragments, and phospholipids, according to data from various model systems. Hydrolyzed species, such as bis(chlorodiorganotin) oxides and triorganotin hydroxides, could also occur for the n-butyltin and phenyltin species.The moieties Me2SnIV and Alk3SnIV (Alk = Me, Et, nBu), present as the hydrolysis products Me2Sn(OH)2 and Alk3SnOH at physiological pH in the aqueous phase (eventually coordinated by donor atoms from buffers), react with thiol groups of model molecules, as well as of feline and rat hemoglobin, forming tetrahedral or trigonalbipyramidal tin sites characterized by covalent Sn—S bonds (C2SnS, C2SnS2 and C3SnS skeletons); tin atoms are eventually further coordinated by nitrogen donors from amino acid fragments or from buffers, as well as by hydroxyl oxygen.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aoc.590060205
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  • 5
    Electronic Resource
    Electronic Resource
    A 119Sn Mössbauer spectroscopic study on complexes of di-and tri-organotin(IV) moieties with 2-mercaptoethanesulfonates, in the solid state and in aqueous solution (1988)
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 2 (1988), S. 457-461 
    Details
    ISSN: 0268-2605
    Keywords: Organotin ; 2-mercaptoethanesulfonates ; solid state ; solution ; Mössbauer spectra ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The configuration of the bonding environment of tin in the complexes [R2Sn(SCH2CH2SO3)2]2- (R = Me, Ph) and [Me3Sn(SCH2CH2SO3)]- has been determined to be tetrahedral both in the solid state and in aqueous solution (for the methyl derivatives). The coordination number of tin increases to five in aqueous solutions for the Me2Sn(IV) complexes in Hepes buffer (N-2-hydroxyethylpiperazine-N′-2-ethanesulfonic acid; at least in fivefold excess, at pH 7.4) due to coordination by the tertiary amino nitrogen atom. No effect is detected due to the surfactant 2-hydroxypropylcellulose concerning both coordination to tin and influence on the Mössbauer parameters. The stoichiometry of mixed complex formation in aqueous solution of Me2Sn(IV), 2-mercaptoethanesulfonate and Hepes is 1:2:1, according to a procedure of ‘Mössbauer titration’. All complexes in aqueous solution undergo slow lysis of the tin-sulfur bonds. Structural assignments have been generally effected on the basis of the magnitude of experimental values of Mössbauer nuclear quadrupole splittings, measured at 77 K for both solid and frozen aqueous absorbers, and comparison with data calculated by the point-charge model approach.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aoc.590020508
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