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

Crystal structure and Hirshfeld surface analysis of (1H-imidazole-κN3)[N-(2-oxido-benzyl-idene)tyrosinato-κ3O,N,O']copper(II)

The title copper(II) complex, [Cu(C16H13NO4)(C3H4N2)], consists of a tridentate ligand synthesized from l-tyrosine and salicyl-aldehyde. One imidazole mol-ecule is additionally coordinating to the copper(II) ion. The crystal structure features N-H⋯O, O-H⋯O and C-H⋯O hydrogen bonds. The Hirshfeld surface analysis indicates that the most important contributions to the packing are from H⋯H (37.9%), C⋯H (28.2%) and O⋯H/H⋯O (21.2%) contacts.

Photofunctions in Hybrid Systems of Schiff Base Metal Complexes and Metal or Semiconductor (Nano)Materials

Composite materials very often provide new catalytic, optical or other physicochemical properties not observed for each component separately. Photofunctions in hybrid systems are an interesting topic of great importance for industry. This review presents the recent advances, trends and possible applications of photofunctions of hybrid systems composed of Schiff base metal complexes and metal or semiconductor (nano)materials. We focus on photocatalysis, sensitization in solar cells (DSSC-dye sensitized solar cell), ligand-induced chirality and applications in environmental protection for Cr(VI) to Cr(III) reduction, in cosmetology as sunscreens, in real-time visualization of cellular processes, in bio-labeling, and in light activated prodrug applications.

Synthesis, structural and electrochemical properties of a new family of amino-acid-based coordination complexes

Metalloproteins involved in oxidation-reduction processes in metabolism are fundamental for the wellbeing of every organism. The use of amino-acid-based compounds as ligands for the construction of biomimetic coordination systems represents a promising alternative for the development of new catalysts. Herein is presented a new family of copper, zinc and nickel coordination compounds, which show four-, five- and six- coordination geometries, synthesized using Schiff base ligands obtained from the amino acids L-alanine and L-phenylalanine. Structural analysis and property studies were performed using single-crystal X-ray diffraction data, spectroscopic and electrochemical experiments and DFT calculations. The analysis of the molecular and supramolecular architectures showed that the non-covalent interactions developed in the systems, together with the identity of the metal and the amino acid backbone, are determinants for the formation of the complexes and the stabilization of the resultant geometries. The Cu^II complexes were tested as candidates for the electrochemical conversion reduction of nitrite to NO, finding that the five-coordinate L-phenylalanine complex is the most suitable. Finally, some insights into the rational design of ligands for the construction of biomimetic complexes are suggested.

Crystal structure and Hirshfeld surface analysis of (aqua-κO)(methanol-κO)[N-(2-oxido-benzyl-idene)threoninato-κ3 O,N,O']copper(II)

In the title complex mol-ecule, [Cu(C11H11NO4)(CH4O)(H2O)], the Cu atom is coordinated in a distorted square-pyramidal geometry by a tridentate ligand synthesized from l-threonine and salicyl-aldehyde, one methanol mol-ecule and one water mol-ecule. In the crystal, the mol-ecules show intra- and inter-molecular O-H⋯O hydrogen bonds. The Hirshfeld surface analysis indicates that the most important contributions to the packing are H⋯H (49.4%) and H⋯O/O⋯H (31.3%) contacts.

Electron Transfer via Helical Oligopeptide to Laccase Including Chiral Schiff Base Copper Mediators

The oxygen reduction efficiency of a laccase-modified electrode was found to depend on the chirality of the oligopeptide linker used to bind the enzyme to the surface. At the same time, the electron transfer between the cathode electrode and the enzyme is improved by using a copper(II) complex with amino-acid derivative Schiff base ligand with/without azobenzene moiety as a mediator. The increased electrochemical current under both O2 and N2 proves that both the mediators are active towards the enzyme.

Photochemical reduction of Cr(vi) compounds by amino acid Schiff base copper complexes with a hydroxyl group and titanium oxide composites in aqueous solutions

The photo-driven reduction reaction of Cr(vi) to Cr(iii) by Schiff base Cu(ii) complexes was studied in aqueous and methanol solutions. The Cr(vi) reduction ratio with the CuVDB–TiO₂ system reached 91%.