苯甲醛缩氨基硫脲铜(Ⅱ)配合物为载体的高选择性硫氰酸根离子电极的研究

Study on Highly Selective Thiocyanate Electrode Based on Benzaldehyde Thiosemicarbazone Copper(Ⅱ) Complex as Neutral Carriers

以苯甲醛缩氨基硫脲铜(Ⅱ)[Cu(Ⅱ) L2]为中性载体的PVC膜电极对硫氰酸根离子(SCN-)具有优良的电 位响应特性并呈现出反Hofmeister选择性行为,其选择性从大到小的次序为:SCN-,Sal-,ClO-4,I-,Cl-,Br-, Ac-,NO-2,NO-3,SO2-4.电极在pH5.0的磷酸盐缓冲体系中,在1.0×10-1～2.5×10-6mol/LSCN-浓度范围呈 近能斯特响应,斜率为56.0mV(25℃),检测下限为9.0×10-7mol/L.采用交流阻抗技术和紫外可见光谱技术初 步研究了阴离子与载体的作用机理;结果表明,配合物中心金属原子的结构以及载体本身的结构与电极的响应行 为之间有非常密切的构效关系.该电极具有响应快、重视性好、检测限低、制备简单等优点.

A new highly selective thiocyanate electrode based on benzaldehyde thiosemicarbazone copper(Ⅱ) complex [Cu(Ⅱ)-L_2] as neutral carrier is developed, which dispays an anti-Hofmeister selectivity sequence: SCN^-,Sal^-,ClO^-_4,I^-,Cl^-,Br^-,Ac^-,NO^-_2,NO^-_3,SO^(2-)_4. The electrode exhibits Nernstian potential linear range to thiocyanate from 1.0×10^(-1) to 2.5×10^(-6) mol/L with a detection limit 9.0×10^(-7) mol/L and a slope of 56.0 mV in pH 5.0 of phosphoratc buffer solution at 25 ℃. The response mechanism is discussed in view of the a.c. impedance technique and the UV spectroscopy technique. These deviations result from the direct interaction between the central metal and the analyte ion and steric effect associated with the structure of the carrier. The electrode has the advantages of simplicity, fast response, fair stability and reproducibility, low detection limit.