Capacità sequestrante di leganti S-donatori nei confronti di CH3Hg+

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[automatically translated] The interest in the coordination chemistry of mercury (II) derives from its intrinsic toxicity. Although all forms of mercury are toxic, the environmental and human effects are usually related to environmental change of inorganic Hg to methylmercury. The high toxicity of methylmercury (II) for humans arises on the affinity of mercury (II) in respect of cysteinyl residues sulfides. The low molecular weight thiols constitute the carriers for the transport and distribution of mercury in the human organism due to the phenomenon of "molecular mimicry." A study of the chemistry of methylmercury in solution (II) in the presence of such binders therefore provides information useful insights about the nature and extent of the interactions between them. Such information can be used to assess metal removal methods from biological systems through the use of chelating agents (chelation therapy). This paper reported a study of the complexing ability of sulfur donor ligands against CH3Hg +. The binders are considered: the acid 2 mercaptopropanoico (or thiolactic, tla), the 3-mercaptopropanoico acid (MPA), the 2-mercaptosuccinic acid (or thiomalic, tma), the penicilammina (pen), cysteine (cys ) and glutathione (gsh). The study was performed by means of different instrumental techniques: potentiometry (ISE-H +) in order to determine the formation constants of the complexes for the different CH3Hg + -legante systems; calorimetry to determine the relative enthalpies of formation; 1H NMR spectroscopy and mass spectrometry-electrospray (ESI-MS) to confirm speciation models proposed and to obtain structural information. The studies were conducted as NaNO3 at I = 0.1 mol L-1 eat = 25 ° C, in the presence of iodide as a competitive binder. For CH3Hg + -tma systems, -pen -gsh and has also studied the dependence of the thermodynamic parameters of complex formation on the ionic strength in the range 0 ≤ I ≤ 1 mol L-1 (NaNO3). The experimental data have shown the formation for all of the species ML systems with a high stability (logβ = 16.06-17.94) and MLH species, in addition to MLH2 (for pen and gsh) and MLOH (for tla, mpa and tma ).
Original languageItalian
Number of pages1
Publication statusPublished - 2010

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