Epitaxial electrodeposition of chiral CuO films from copper(ii) complexes of malic acid on Cu(111) and Cu(110) single crystals

Abstract

Chiral films of CuO were anodically electrodeposited onto Cu(111) and Cu(110) single crystals from alkaline solutions of Cu(II) complexed with the malate ion. The chirality of the film was directed by the chiral solution precursor. X-Ray diffraction pole figures and stereographic projections were used to determine the absolute configuration of the films. CuO films grown on Cu(111) from L-malate had (11) and (311) orientations and the films grown from D-malate had (1) and () orientations. CuO films grown on Cu(110) from L-malate had (110) and (31) orientations, whereas the films grown from D-malate deposition bath had (0) and (1) orientations. The CuO films grown from a racemic malate bath showed only the (11) and (1) orientations on Cu(111) and (110) and (0) orientations on Cu(110). Single crystals of L-, D- and DL-bis(malato)copper(II) dihydrate complexes were synthesized and the structures were determined with X-ray crystallography. The chiral complexes of bis(malato)copper(II) dihydrate were each found to belong to the monoclinic space groupP2₁ whereas the racemic complex belonged to the centrosymmetric P2₁/c space group. The chiral complexes formed coordination polymers along the b-axis, with the carboxyl group from each complex linking to the axial site of an adjacent Cu(II) complex. In the complex produced from the racemic mixture, no coordination polymers formed.