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1.
Dalton Trans ; 40(2): 506-13, 2011 Jan 14.
Artigo em Inglês | MEDLINE | ID: mdl-21088793

RESUMO

A series of platinum(II) complexes of the type [Pt(trpy)L](NO(3))(n) (L = 3- or 4-pyridineboronic acid (3- or 4-pyB, respectively), n = 2; HL = 4-mercaptophenylboronic acid (HmpB), n = 1; trpy = 2,2':6',2''-terpyridine) and [{Pt(trpy)}(2)(µ-pzB)](NO(3))(3) (HpzB = 4-pyrazoleboronic acid) were synthesized and fully characterized by means of multinuclear ((1)H, (13)C, (11)B, and (195)Pt) 1D- and 2D-NMR spectroscopy and elemental analysis. The triflate derivatives [Pt(trpy)(4-pyB)](OTf)(2) and [{Pt(trpy)}(2)(µ-pzB)](OTf)(3) were also prepared, and their molecular structures were confirmed by X-ray crystallography. Variable pH (1)H NMR spectroscopy showed that hydroxylation of the boronic acid group occurs in aqueous solution at pH > 5 and the pK(a) values for the complexes were determined. In buffered aqueous solution (pH 7.4), the complexes bind strongly to simple diols such as catechol and monosaccharides including D-fructose, D-ribose, D-sorbitol and D-mannitol, as determined by isothermal titration calorimetry (ITC). The equilibrium binding constants for these reactions were determined and were found to exceed those of organic boronic acids such as phenylboronic acid by an order of magnitude or greater, an effect that can be directly attributed to the cationic charge of the complexes. 2D-NMR methods (HSQC and HMBC) were used to elucidate the structures of the carbohydrate adducts [Pt(trpy)(3-pyB)]·D-fructose·NO(3) and [Pt(trpy)(4-pyB)]·D-fructose·NO(3) in aqueous solution. DNA-binding experiments with calf-thymus DNA (CT-DNA) indicate an avid DNA-binding interaction by the mononuclear complexes, as determined using thermal melting methods and ITC, but the behaviour of the dinuclear species [{Pt(trpy)}(2)(µ-pzB)](NO(3))(3) is complicated and could not be modeled adequately; higher ionic strength solutions and lower temperatures resulted in a similar DNA binding interaction to the mononuclear complexes. The presence of excess d-fructose did not significantly affect the binding of the platinum(II)-trpy complexes to CT-DNA.


Assuntos
Ácidos Borônicos/química , Complexos de Coordenação/síntese química , DNA/química , Monossacarídeos/química , Platina/química , Calorimetria , Catecóis/química , Complexos de Coordenação/química , Cristalografia por Raios X , Ligantes , Espectroscopia de Ressonância Magnética , Conformação Molecular , Temperatura de Transição
2.
Acta Crystallogr Sect E Struct Rep Online ; 65(Pt 6): m690, 2009 May 29.
Artigo em Inglês | MEDLINE | ID: mdl-21583047

RESUMO

The asymmetric unit of the title compound, [SnCl(4)(C(12)H(8)N(2))]·0.5C(2)H(4)Cl(2), contains a tin complex and one disordered half-mol-ecule of the solvent dichloro-ethane [occupancies 0.71 (2):0.29 (2)]. The six coordinate Sn(IV) atom adopts a distorted octa-hedral geometry. π-π inter-actions between adjacent aromatic rings [interplanar distance 3.483 (5) Å] seem to be effective in the stabilization of the crystal packing.

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