Kaur Navneet, Kumar Subodh
Department of Chemistry, Guru Nanak Dev University, Amritsar, India.
Dalton Trans. 2006 Aug 21(31):3766-71. doi: 10.1039/b601558a. Epub 2006 Apr 26.
Chromogenic receptors 2 and 3 undergo distinct colour changes from magenta to blue on gradual addition of Cu(II) and can be used as colorimetric probes for spectrophotometric and visual analysis of Cu(II) in the presence of biological metal ions Na(I), K(I), Mg(II), Ca(II), Fe(II), Zn(II) etc. in aqueous solution (methanol-water 1 : 1 v/v). On addition of Cu(II), both 2 and 3 exhibit a bathochromic shift of Delta lambda(max) = 114 nm for 2 and Delta lambda(max)= 150 and 265 nm for receptor 3. The protonation constants and formation constants of Cu(II) complexes of receptors 2 and 3 (at pH 7) and the effect of pH on formation of these complexes has been determined by the combination of UV-vis-pH titrations of receptors 2 and 3 and their Cu(II) complexes. These results and the emergence of only one peak at 610 nm for 2 and two distinct absorption peaks at 715 and 800 nm for 3 on addition of Cu(II) unambiguously point to mono- and di-deprotonation for 2 and 3, respectively.
在逐步加入Cu(II)时，生色受体2和3会发生从品红色到蓝色的明显颜色变化，并且在水溶液（甲醇 - 水1:1 v/v）中存在生物金属离子Na(I)、K(I)、Mg(II)、Ca(II)、Fe(II)、Zn(II)等的情况下，可用作比色探针用于分光光度法和目视分析Cu(II)。加入Cu(II)时，受体2和3都表现出红移，受体2的Δλ(max) = 114 nm，受体3的Δλ(max) = 150和265 nm。通过受体2和3及其Cu(II)配合物的紫外 - 可见 - pH滴定相结合，测定了受体2和3的Cu(II)配合物的质子化常数和形成常数（在pH 7时）以及pH对这些配合物形成的影响。这些结果以及加入Cu(II)时受体2在610 nm处仅出现一个峰，受体3在715和800 nm处出现两个不同吸收峰，明确表明受体2和3分别发生了单去质子化和双去质子化。
