非负矩阵分解法研究三价铁离子与试钛灵形成的多组分体系

采用分光光度法测量三价铁离子与邻苯二酚-3,5-二磺酸钠(试钛灵)的配位数和稳定常数是常见的大学化学教学实验之一。我们发现,随着溶液中三价铁离子与试钛灵配比的改变,配合物的吸收光谱峰位置发生显著位移,推断配位数不唯一。用非负矩阵分解法对系列光谱数据进行分析,获取主要成分的特征光谱和它们的化学配比,结果显示体系中包含两种产物,分别对应一配位和二配位两种形式。然而,教材要求给出一个正整数的配位数,实验设计的合理性值得探讨。

Investigation of Multicomponents of Iron(III) Complexes with Tiron by Non-negative Matrix Factorization

The coordination number and dissociation constant measurement of complex consisting of Iron(III) and Tiron has been widely employed as a teaching experiment in university. However, with the ratio of Iron(III) and Tiron varying a distinct absorption peak shifts have been observed, indicating the non-unique complex in solution. Non-negative matrix factorization was applied to analyses the spectra data, and the characteristic spectrum and coordination number of each component were obtained. The results shows the coexistence of mono- and bis-tiron complexes of Iron(III) in the solution, and this does challenge the rationality of this system as a teaching experiment because the coordination number should be positive integer according to the text book.