Synthesis, structural characterization and in vitro biological screening of some homoleptic copper(II) complexes with substituted guanidines

A series of homoleptic copper(II) complexes (1a–8a) with N,N′,N″-trisubstituted guanidines, [Cu(II){PhCONHC(NHR)NPh}2] (where R = phenyl (1a), n-butyl (2a), sec-butyl (3a), cyclohexyl (4a), 1-naphthyl (5a), 2,4-dichlorophenyl (6a), 3,4-dichlorophenyl (7a), and 3,5-dichlorophenyl (8a)) have been synthesized and characterized by elemental analyses, FT-IR, UV–visible, 1H and 13C NMR spectroscopy, and single crystal X-ray diffraction analysis. The X-ray crystal structures revealed that the complexes 2a and 4a are mononuclear in the solid state and that the geometry around the copper atom is nearly square planar. In both the cases, N,N′,N″-trisubstituted guanidine ligands have been coordinated to the Cu(II) through the oxygen and nitrogen atoms. The synthesized guanidines and their complexes were initially screened for their anti-microbial activities, and Brine Shrimps Lethality assay. The complexes were also screened for in vitro cytotoxicity activity in human cell lines carcinomas A498, EVSAT, H226, IGROV, M19, MCF-7 and WIDR. The results show a moderate level of cytotoxicity against these seven human cancer cell lines as compared with standard chemotherapeutic drugs.

Graphical abstractA series of homoleptic copper(II) complexes(1a-8a) with N,N’,N”-trisubstituted guanidines (1-8), have been synthesized, characterized and screened for in vitro cytotoxicity activity in human cell lines carcinomas A498 (Renal), EVSAT (Breast), H226 (Lung), IGROV (Ovarian), M19 (Melanoma-Skin), MCF-7 (Breast) and WIDR (Colon), showing a moderate level of cytotoxicity against these cancer cell lines as compared with standard chemotherapeutic drugs.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► N,N’,N"-trisubstituted guanidines are of biological and medicinal importance. ► The copper(II) complexes have been screened for their biological applications. ► These studies constitute a useful reference basis for future investigations. ► The X-ray diffraction analysis of 1, 2a and 4a were obtained and studied. ► The UV–visible studies confirm the stability of complexes in solution phase.