摘要:
The coordination of Me2Sn(IV)(2+) (=M) to captopril {N-[(S)-3-mercapto-2-methylpropionyl]-L-proline, = H-2(cap), H2L} in aqueous solution was studied by means of potentiometric titration, electrospray mass spectrometry, H-1-NMR spectroscopy and Mossbauer spectroscopy in the pH range 2-11 (I = 0.1 mol dm(-3) NaClO4, 298 K). The results obtained with these methods proved that only monomeric complexes are formed in solution. In the acidic pH range, species with a metal-to-ligand ratio of 1:1 exist. The neutral complex ML, similarly to the complex Me2Sn(cap) crystallized in the same pH range, adopts a tbp structure with eq -S- and ax -COO-, while, instead of the coordination of the amide -C=O, observed in the solid state, the other ax position is occupied by a H2O molecule. With increasing pH, in the neutral and weakly basic pH range the complexes MLH-1 and ML2 are formed, in which the -COO- group is displaced from the coordination sphere by an OH- and an S- of another ligand, respectively. Biological activity tests on Me2Sn(cap) and three further R2Sn(IV) captopril complexes showed that n-Bu2Sn(cap) and t-Bu2Sn(cap) exert toxic activity towards the embryos of Ciona intestinalis, while the ligand itself does not affect the development of the embryos to any significant extent; Me2Sn(cap) and Et2Sn(cap) produced normal swimming larvae. (C) 2003 Elsevier Science B.V. All rights reserved.