Synthesis, crystal structure, antiproliferative activity, DNA binding and density functional theory calculations of 3-(pyridin-2-yl)-8-tert-butylcoumarin and its copper(II) complex

Abstract

A Cu(II)–coumarin complex, [CuL2(NO3)2] (2), where L = 3-(pyridin-2-yl)-8-tert-butylcoumarin (1), was synthesized with Cu(NO3)2⋅3H2O and characterized using elemental, infrared and single-crystal X-ray diffraction analyses. The crystal structure of 1 shows that all the pyrone, benzene and pyridine rings are completely coplanar. The crystal structure of 2 is stabilized by intermolecular C–H···O and C–H···N hydrogen bonds and C···C short contacts, which lead to the formation of a two-dimensional network structure. Density functional theory results give support to the experimentally determined monomeric structure. The in vitro cytotoxic activities of 1 and 2 were investigated against HeLa (cervical carcinoma), A549 (lung), HepG2 (liver) and HUVEC (umbilical vein) cells by MTT assay. The IC50 values show that both 1 and 2 have lower toxicity than doxorubicin and cisplatin in every case. Ligand 1 exhibits higher anti-HeLa activity than doxorubicin. Complex 2 displays higher anti-HeLa activity than coumarin but lower than that of cisplatin. Various spectroscopic approaches indicate that 1 and 2 could effectively bind with DNA through intercalation mode.