Highly Selective Thiocyanate Electrode Based on Bis‐bebzion Schiff Base Binuclear Copper(II) Complex as Neutral Carrier

Abstract

A highly selective polyvinyl chloride (PVC) membrane electrode, based on N,N′‐(aminoethyl)ethylenediamide bis(2‐benzoideneimine) binuclear copper(II) complex [Cu(II)‐AEBB] as neutral carrier, was prepared for thiocyanate (SCN⁻) determination, which displays an anti‐Hofmeister selectivity sequence for a series of anions in the following order: SCN⁻>ClO₄ ⁻>Sal⁻ > I⁻>NO₃ ⁻>Br⁻> Cl⁻>NO₂ ⁻>SO₃ ²⁻>F⁻>H₂PO₄ ⁻>SO₄ ²⁻. The electrode exhibited near‐Nernst response for SCN⁻ with a slope of –59.0 mV/decade over a wide concentration range (8.5×10⁻⁷∼6.8×10⁻¹ mol/L) with a detection limit of –5.0×10⁻⁷ mol/L in pH 5.0 phosphate buffer solution at 25°C. Alternating current (AC) impedance and equivalent circuits were used to investigate the thiocyanate response mechanism of the membrane doped with [Cu(II)‐AEBB].

Keywords:

• N,N′‐(aminoethyl)ethylenediamide bis(2‐benzoideneimine) binuclear copper(II)
• Schiff base
• selective electrode
• thiocyanate
• potentiometric response characteristic

The support of the National Natural Science Foundation of China (20675064), and the Natural Science Foundation of Chongqing City, China is gratefully acknowledged (No. CSTC‐2004BB4149, 2005BB4100).