Lu(iii) bis-phthalocyanines containing carbazole moieties: synthesis, characterization, electrochemical properties and sensor applications

Abstract

A new range of sandwich type tetra and octa bis-phthalocyanines (Car-Pc₂-1 and Car-Pc₂-2) starting from commercially available N-ethylcarbazole were successfully prepared whereby two phthalocyanine moieties are connected with a lutetium ion. Structural characterization of Lu(III) bis phthalocyanines (Lu(III)bisPc) was performed by ¹H NMR, ¹³C NMR, infrared (IR), UV-vis-NIR, and MALDI-TOF spectroscopic techniques. The electrochemical properties of bis-phthalocyanines were characterized using cyclic voltammetry (CV) and square wave voltammetry (SWV). Lu(III)bisPcs were then electropolymerized on glassy carbon electrodes (GCE). Furthermore, new modified electrodes with the electropolymerization of Lu(III) bisPc by doping with graphane were developed in order to detect low concentrations of ascorbic acid (AA), dopamine (DA) and uric acid (UA). The surface morphologies of the hybrid electrodes were investigated using SEM/EDX, UV-Vis, IR and Raman spectroscopies. The sensing behavior of the modified electrodes was also tested to detect AA, DA and UA analytes. The Grp/Car-Pc₂-1/GCE electrode selectively detected AA with a limit of detection (LOD) of 1.56 μM, while LOD values of Ply(Car-Pc₂-2)/GCE and Grp/Ply(Car-Pc₂-2)/GCE were determined to be 0.16 μM and 1.07 μM for DA and UA, respectively, by voltammetric analyses. Moreover, the modified electrodes were also applied to detect AA, DA and UA in tap water samples using the standard addition method with satisfactory results.