Synthesis, spectral, antitumor and antimicrobial studies on Cu(II) complexes of purine and triazole Schiff base derivatives

•A new series of Schiff bases of purine and triazole have been synthesized in addition to their Cu(II) complexes.•The structures of the prepared compounds have been investigated by different spectroscopic techniques.•The biological and anti-tumor activities for some complexes have been evaluated. A series of copper (II) complexes of Schiff bases derived from 7H-2,6-diaminopurine and 4H-3,5-diamino-1,2,4-triazole with 2-pyridinecarbaldehyde, salicylaldehyde, 2,4-dihydroxybenzaldehyde and 2-hydroxy-1-naphthaldehyde have been prepared. The donor atoms and the possible geometry of the complexes were investigated by means of elemental and thermal analyses, molar conductance, magnetic moment, UV–Vis, IR, ESR and mass spectra. The ligands behaved as tetradentate, coordinating through the nitrogen atom of the azomethine group and the nearest nitrogen atom to it or oxygen atom of α-hydroxyl group. The results of simultaneous DTA & TGA analyses of the complexes showed the final degradation product for these complexes is CuO. The spectral studies confirmed a four coordinate environment around the metal ion. The obtained results were supported by 3D molecular modeling of complexes using molecular mechanics (MM+) and semiempirical molecular orbital calculations (PM3). These complexes were also tested for their in vitro antimicrobial activities against some bacterial and fungal strains. Complex 2 was investigated for its cyctotoxic effect against human breast cancer (MCF7), liver carcinoma (HEPG2) and colon carcinoma cell lines (HCT116). This compound exhibited a moderate activity against the tested cell lines with IC50 of 10.3, 9.8 and 8.7μg/ml against MCF7, HCT116 and HEPG2, respectively.