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用分光光度法研究了镧系离子La(Ⅲ)、Nd(Ⅲ)和Gd(Ⅲ)的二甲酚橙(XO)螯合物水溶液的可逆热致变色规律。测定了螯合物的组成及条件稳定常数。探讨了体系酸度、离子强度及配体浓度对热致变色作用的影响。初步研究表明,Ln(Ⅲ)-XO螯合物水溶液中存在两种不同颜色的螯合物质子离解平衡:体系呈现的热致变色作用是平衡常数随温度而变化所致。
The reversible thermochromism of Xe chelates in lanthanide ions La (Ⅲ), Nd (Ⅲ) and Gd (Ⅲ) was studied by spectrophotometry. The chelate composition and the stability constants were determined. The effect of system acidity, ionic strength and ligand concentration on thermochromism was discussed. Preliminary studies have shown that there are two dissociation equilibriums of chelates in Ln (Ⅲ) -XO chelate aqueous solution: the thermochromism exhibited by the system is due to the change of the equilibrium constant with temperature.