Synthesis and characterization of a new copper(II) polymer containing a thiocyanate bridge and its application in dopamine detection

Abstract

Reaction of bis(3,5-dimethyl-1-pyrazolyl)methane (L) with CuCl2 and NaNCS yielded the new coordination polymer [Cu2(μ-SCN)3(L)2] (I), which was isolated as a brown and air-stable solid. The new compound was characterized by melting point measurement, elemental analysis, mass spectra, thermogravimetric analysis, magnetic moment, and Raman, Infrared and Ultraviolet/Visible spectroscopy. In addition, the structure of the compound was determined by single-crystal X-ray diffraction. As an application, the copper polymer was used to modify a fluorine-doped tin oxide (FTO) electrode covered with poly(3,4-ethylenedioxythiophene). This electrode was tested for the detection of dopamine (DA) in the presence of ascorbic acid (AA) in a PBS solution at pH 7.4. The presence of the new copper polymer diminished the charge transfer resistance of the surface allowing the detection of DA by differential pulse voltammetry. The calibration curves for DA showed two linear ranges from 0.6 to 9.0μM and from 10.0 to 200.0μM. The sensitivity of the lowest concentration range was 0.336μAμM−1cm−2.