Kinraide Thomas B
Agricultural Research Service, US Department of Agriculture, Beaver, West Virginia 25813-9423, USA.
Environ Toxicol Chem. 2009 Mar;28(3):525-33. doi: 10.1897/08-208.1. Epub 2008 Nov 3.
Ten scales relating to chemical hardness or softness of metal ions were compiled. These included eight published scales such as those of Pearson, Ahrland, Klopman, and Misono. Another scale consisted of the logs of the solubility products of metal sulfides, and yet another was a consensus scale constructed from -log K values for metal ion binding to seven soft ligands. These 10 scales were normalized and averaged. The resulting consensus scale for softness (sigma(Con)) appeared to be superior to any of the 10 scales used in its construction based on correlations among the scales. Other possible indicators of softness were examined, including the standard electrode potential (E(0)) and the bulk metal density (rho(Metal)), both of which were also superior to most of the 10 scales just mentioned. Vales for sigma(Con) may be computed from E(0), rho(Metal), and the first ionization potential (I(P)), R(2) = 0.867, for the equation sigma(Con) = aE(0)I(P) + brho(Metal). A consensus scale for toxicity (T(Con)) derived from studies with many different taxa correlated well (R(2) = 0.807) with sigma(Con) computed from the preceding equation, but incorporation of ion charge (Z) into the following equation, T(Con) = asigma(Con) + bsigma(Con)Z + cZ, increased R(2) to 0.923. Substitution of other softness scales for sigma(Con) into equations to predict T(Con) reduced the value of R(2). Thus, sigma(Con) appears to be a superior scale for metal ion softness and toxicity, the latter being an interactive function of both softness and charge.
编制了10个与金属离子化学硬度或软度相关的标度。其中包括8个已发表的标度，如皮尔逊、阿尔兰、克洛普曼和水野的标度。另一个标度由金属硫化物的溶度积对数组成，还有一个是根据金属离子与7种软配体结合的-log K值构建的共识标度。对这10个标度进行了归一化和平均。由此得到的软度共识标度（σ(Con)）基于标度之间的相关性，似乎优于构建它时所使用的10个标度中的任何一个。还研究了其他可能的软度指标，包括标准电极电位（E(0)）和金属本体密度（ρ(Metal)），这两个指标也优于上述提到的10个标度中的大多数。对于方程σ(Con)=aE(0)I(P)+bρ(Metal)，σ(Con)的值可由E(0)、ρ(Metal)和第一电离能（I(P)）计算得出，R² = 0.867。从对许多不同分类群的研究中得出的毒性共识标度（T(Con)）与根据上述方程计算出的σ(Con)相关性良好（R² = 0.807），但将离子电荷（Z）纳入以下方程T(Con)=aσ(Con)+bσ(Con)Z + cZ后，R²增加到了0.923。将其他软度标度代入预测T(Con)的方程中会降低R²的值。因此，σ(Con)似乎是金属离子软度和毒性的一个优越标度，后者是软度和电荷的相互作用函数。
