Binding ability of glutathione towards alkyltin(IV) compounds in aqueous solution.

The interactions between glutathione (H3GSH) and (CH3)2Sn(2+), (CH3)3Sn(+), (C2H5)3Sn(+) and (C3H7)3Sn(+) cations were studied by potentiometry, UV spectrophotometry, (1)H NMR spectroscopy and electrospray mass spectrometry (ESI MS). Potentiometric measurements evidenced speciation models very similar for all the alkyltin(IV) cation-GSH(3-) systems, with the formation of M(GSH)(z-3), M(GSH)H(z-2) and M(GSH)H2(z-1) species [M(z+)=(CH3)2Sn(2+), (CH3)3Sn(+), (C2H5)3Sn(+), or (C3H7)3Sn(+)] and, for dimethyltin(IV) cation, also the mixed hydrolytic M(GSH)(OH)(2-) one. The equilibrium behavior in NaCl aqueous solution, at different ionic strengths and temperatures, is discussed.

Sequestering ability of some chelating agents towards methylmercury(II).

A study on the interactions between CH(3)Hg(+) and some S, N and O donor ligands (2-mercaptopropanoic acid (thiolactic acid (H(2)TLA)), 3-mercaptopropanoic acid (H(2)MPA), 2-mercaptosuccinic acid (thiomalic acid (H(3)TMA)), D,L-penicillamine (H(2)PSH), L-cysteine (H(2)CYS), glutathione (H(3)GSH), N,N'-bis(3-aminopropyl)-1-4-diaminobutane (spermine (SPER)), 1,2,3,4,5,6-benzenehexacarboxylic acid (mellitic acid (H(6)MLT)) and ethylenediaminetetraacetic acid (H(4)EDTA)) is reported. The speciation models in aqueous solution and the possible structures of the complexes formed are discussed on the basis of potentiometric, calorimetric, UV spectrophotometric and electrospray mass spectrometric results. For the CH(3)Hg(+)-S donor ligand systems, the formation of ML(1-z) and MLH(2-z) complex species is observed, together with a diprotonated MLH(2)(3-z) species for CYS(2-), PSH(2-) and GSH(3-) and the mixed hydrolytic one ML(OH)(-z) for TLA(2-) and MPA(2-).