Photochemical reaction of amino acid Schiff base derived Cu complexes with extended π-system and their titanium oxide composites

Synthesis of Cu(II) complexes with condensation products of 2-hydroxy-1-naphthaldehyde and three amino acids (L-alanine, L-valine and L-phenylalanine) is reported and their physicochemical properties are compared with the previously studied Schiff base Cu(II) complexes. The synthesized complexes were characterized by single-crystal X-ray diffraction and by optical spectroscopy. DFT-optimized geometries of the complexes were used in TD-DFT calculations for assignment of UV-Vis spectra. The UV-Vis light-driven photo-catalytic activity towards the reduction of Cr(VI) to Cr(III) was studied in methanol for both as-prepared complexes and the ones linked with TiO₂. In all cases the reduction occurred more efficiently than with pure TiO₂ or methanol.