Thiophene-containing β-diketonate complex of copper(II): X-ray crystal structure and electropolymerization

Abstract

In this work, we report the synthesis of the asymmetrical β-diketone 1-(thiophen-2-yl)-3-(thiophen-3-yl)propane-1,3-dione (HL) and its corresponding bis(β-diketonate)copper(II) complex [Cu{1-(thiophen-2-yl)-3-(thiophen-3-yl)-1,3-propanedionate}2] (CuL2), isolated in 60 and 86% yields, respectively. These two new compounds have been characterized by elemental analysis, FT-IR and UV–Vis spectroscopy and, in the case of HL, by 1H and 13C NMR spectroscopy. Additionally, both compounds were authenticated by X-ray diffraction analysis. The β-diketone HL exists as its keto-enol tautomer both in solution and in the solid-state with the OH group adjacent to the 3-thienyl unit. The CuL2 is essentially flat and the Cu(II) center adopts a perfect square planar geometry. The CuL2 modified electrode was fabricated through the electropolymerization of the monomer in a 0.1M of tetrabutylammonium tetrafluoroborate (TBATFB) in anhydrous acetonitrile solution, in the potential window −1.0V to 1.6V. The thin film Pt|(CuL2)n modified electrode response was studied employing a 0.1M of TBATFB solution in CH3CN. Likewise, the potentiostatic method was also employed to synthesize the films on Fluorine Doped Tin Oxide electrode (FTO). Images from the electrode surface were obtained using Scanning Electron Microscopy (SEM).