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

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, by¹H and¹³C 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 [sbnd]OH group adjacent to the 3-thienyl unit. The CuL₂is essentially flat and the Cu(II) center adopts a perfect square planar geometry. The CuL₂modified electrode was fabricated through the electropolymerization of the monomer in a 0.1 M of tetrabutylammonium tetrafluoroborate (TBATFB) in anhydrous acetonitrile solution, in the potential window −1.0 V to 1.6 V. The thin film Pt|(CuL₂)_nmodified electrode response was studied employing a 0.1 M 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).