Synthesis, characterization, photoluminescence, antiproliferative activity, and DNA interaction of cadmium(II) substituted 4'-phenyl-terpyridine compounds

Abstract

A series of CdCl₂ complexes (1a-1f and 2a-2c) with 4'-(substituted-phenyl)-2,2':6',2″-terpyridine compounds bearing hydrogen (L^1a), p-methyl (L^1b), p-phenyl (L^1c), p-tolyl (L^1d), p-carboxyl (L^1e), p-fluoro (L^1f), p-hydroxyl (L^2a), m-hydroxyl (L^2b) or o-hydroxyl (L^2c), were prepared and characterized by ¹H NMR, IR, elemental analysis and single crystal X-ray diffraction. All the compounds display interesting photoluminescent properties and different maximal emission peaks due to the difference of the substituent groups. The in vitro antiproliferative activities against four human carcinoma cell lines, A549, Bel-7402, Eca-109 and MCF-7, were investigated and cell viability studies indicate that the compounds have excellent results with the lowest IC₅₀ values of 0.372 (1c), 1.003 (1c), 1.161 (1b) and 0.231 (1c) μM, respectively. The DNA interaction was studied by fluorescence titration, circular dichroism spectroscopy and molecular modeling methods. Spectrophotometric results reveal that the compounds have strong affinity binding with DNA as intercalators and molecular docking studies indicate that the binding is contributed by the π…π stacking and hydrogen bonds.

Keywords: Antiproliferative activity; Cadmium; DNA interaction; Molecular docking; Photoluminescence; Terpyridine complex.