Synthesis, characterization and in vitro cytotoxicity of Co(II) complexes with N6-substituted adenine derivatives: X-ray structures of 6-(4-chlorobenzylamino)purin-di-ium diperchlorate dihydrate and [Co6(μ-L6)4Cl8(DMSO)10] · 4DMSO

Cobalt(II) complexes of the composition [Co(L1)Cl(H2O)2] · H2O (1), [Co(L2)Cl(H2O)2] · 2H2O (2), [Co(L3)Cl(H2O)2] · H2O (3), [Co(L4)Cl(H2O)2] · H2O (4), [Co(L5)Cl(H2O)2] · H2O (5) and [Co(L6)Cl(H2O)2] · H2O (6), where HL1 = 6-(3-chlorobenzylamino)purine, HL2 = 6-(4-chlorobenzylamino)purine, HL3 = 6-(2,3-dimethoxybenzylamino)purine, HL4 = 6-(3,4-dimethoxybenzylamino)purine, HL5 = 6-(3-fluorobenzylamino)purine and HL6 = 6-(4-fluorobenzylamino)purine, have been prepared. The compounds have been characterized by elemental analyses, ES+ mass, UV–Vis, IR and NMR spectroscopies, magnetic measurements, molar conductances and thermogravimetric analysis as mononuclear tetrahedral high-spin cobalt(II) complexes. In vitro cytotoxicities of the complexes were tested by a Calcein AM assay against the following human tumour cell lines: malignant melanoma (G361), chronic myelogenous erythroleukemia (K562), osteogenic sarcoma (HOS) and breast adenocarcinoma (MCF7). The molecular structures of 6-(4-chlorobenzylamino)purin-di-ium diperchlorate dihydrate, [H2+L2](ClO4)2 · 2H2O, and a hexanuclear Co(II) complex, [Co6(μ-L6)4Cl8(DMSO)10] · 4DMSO (7), have been determined by a single crystal X-ray analysis. To elucidate the manner of the organic ligand coordination to cobalt, the geometry of the complex 2 was optimized using DFT calculations at the B3LYP/6-311+G* level of the theory.

New mononuclear tetrahedral high-spin Co(II) complexes with 6-benzylaminopurine derivatives have been synthesized. The coordination via the N9 atom of the adenine moiety has been confirmed by NMR data and DFT calculations. In vitro cytotoxicity of the complexes against human melanoma, sarcoma, leukaemia and carcinoma cell lines has been determined.Figure optionsDownload as PowerPoint slide