On the interaction of ascorbic acid and the tetrachlorocuprate ion [CuCl4]2− in CuCl nanoplatelet formation from an ionic liquid precursor (ILP)

Abstract

The formation of CuCl nanoplatelets from the ionic liquid precursor (ILP) butylpyridinium tetrachlorocuprate [C₄Py]₂[CuCl₄] using ascorbic acid as a reducing agent was investigated. In particular, electron paramagnetic resonance (EPR) spectroscopy was used to evaluate the interaction between ascorbic acid and the Cu(II) ion before reduction to Cu(I). EPR spectroscopy suggests that the [CuCl₄]²⁻ ion in the neat IL is a distorted tetrahedron, consistent with DFT calculations. Addition of ascorbic acid leads to the removal of one chloride from the [CuCl₄]²⁻ anion, as shown by DFT and the loss of symmetry by EPR. DFT furthermore suggests that the most stable adduct is formed when only one hydroxyl group of the ascorbic acid coordinates to the Cu(II) ion.