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

[Display omitted] •Photocatalytic activity of Cu(II) complexes and their TiO2 hybrid systems was examined.•Photocatalytic activity of Cu(II) complexes based on amino acid Schiff bases was in the order: CuAHN > CuVHN > CuFHN.•For CuAHN hybrid and sole complex, the most effective photocatalytic activity was observed in the region 460–495 nm.•The GGA (BP86) and hybrid (B3LYP) functionals can be used for calculations of redox potentials. 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.