Functional substituted Cu(II) Schiff base complexes, syntheses, X-ray and theoretical characterizations, and investigations of their polyphenol oxidase- and peroxidase-like activities

•Schiff base complex with acrylate substituted group was synthesized.•By X-ray diffraction technique was determined molecular structure of the complex.•Depending on the functional groups of the complexes, enzymatic activity changes were compared. Some Cu(II) Schiff base complexes were synthesized by a template reaction of salicylaldehyde and amino ethanol or aminoethoxyethanol with Cu(OAc)2.H2O in methanol solution as the model compounds for mimic enzymatic activities. The synthesized bidentate ligands were formed one chelate ring via iminic N and phenolic O donor atoms. The resulting complexes were characterized by elemental analysis and FTIR spectroscopy. The FTIR spectra of the complexes showed typical changes for Schiff base coordination when comparing with the FTIR spectrum of the ligand. The molecular and crystal structures of bis (2-((2-hydroxybenzylidene)amino)ethyl acrylate) copper(II), ([Cu(SAE-Acr)2]) compound were clarified by single crystal X-ray diffraction technique. In order to visualize the intermolecular interactions in the crystal of the [Cu(SAE-Acr)2] compound, a Hirshfeld surface (HS) analysis was carried out, and the intermolecular interaction energies were also calculated using the CE–B3LYP/6–31G(d,p) energy model. Polyphenol oxidase and peroxidase-like activities of the synthesized compounds were also investigated. The results showed that Cu(SAE)2 and Cu(SAE-Acr)2 compounds had good polyphenol oxidase and peroxidase-like activities. [Display omitted]