De Stefano Concetta, Milea Demetrio, Sammartano Silvio
Dipartimento di Chimica Inorganica, Chimica Analitica e Chimica Fisica, Università di Messina, Salita Sperone, 31, I-98166 Messina (Vill. S. Agata), Italy.
Biophys Chem. 2005 Jul 1;116(2):111-20. doi: 10.1016/j.bpc.2005.02.005. Epub 2005 Apr 14.
As the introduction of a systematic study on the sequestering ability of phytate (Phy) towards heavy metal and organometal cations, this paper describes the results of an investigation (at t=25 degrees C by potentiometry, ISE-H(+) glass electrode) of its interactions with dimethyltin(IV) cation [(CH(3))(2)Sn(2+), DMT] in NaCl aqueous solutions at different ionic strengths (0.1< or =I (mol L(-1))< or =1), in the pH range 2.5< or =pH< or =8.5 and considering metal to ligand ratios 1:1< or =DMT:Phy< or =4:1. We observed the formation of 18 DMT(i)H(j)Phy((12-2i-j)-) species: with i=1 and 0< or =j< or =7; i=2 and 0< or =j< or =5; i=3 and 0< or =j< or =3. Their complex formation constant values are fairly dependent on ionic strength and this dependence was modeled by a Debye-Hückel type equation. The speciation of phytic acid and dimethyltin(IV) is also dependent on the metal to ligand ratio; the dependence of the stability of phytate-dimethyltin(IV) species on both the phytate protonation step and the number of cations bound to the ligand has been modeled and an empirical predictive relationship is also proposed. From the results obtained it emerged that phytate has very good sequestering ability towards (CH(3))(2)Sn(2+). Comparisons are made with other ligands, such as ethylenediamine-N,N,N',N'-tetraacetic acid (EDTA) and phosphate.
作为对植酸（Phy）对重金属和有机金属阳离子螯合能力的系统研究的引言，本文描述了一项研究结果（在25℃下通过电位滴定法，使用离子选择性电极-H⁺玻璃电极），该研究考察了在不同离子强度（0.1≤I（mol/L）≤1）、pH范围为2.5≤pH≤8.5且金属与配体比例为1:1≤DMT:Phy≤4:1的条件下，植酸与二甲基锡（IV）阳离子[（CH₃）₂Sn²⁺，DMT]在NaCl水溶液中的相互作用。我们观察到形成了18种DMT(i)H(j)Phy((12 - 2i - j)-)物种：其中i = 1且0≤j≤7；i = 2且0≤j≤5；i = 3且0≤j≤3。它们的络合形成常数相当依赖于离子强度，并且这种依赖性通过德拜 - 休克尔型方程进行建模。植酸和二甲基锡（IV）的物种形成也取决于金属与配体的比例；已对植酸 - 二甲基锡（IV）物种稳定性对植酸质子化步骤以及与配体结合的阳离子数量的依赖性进行了建模，并提出了一种经验预测关系。从获得的结果可以看出，植酸对（CH₃）₂Sn²⁺具有非常好的螯合能力。还与其他配体，如乙二胺 - N,N,N',N'-四乙酸（EDTA）和磷酸盐进行了比较。
