Hydrogen-Bonded Organic–Inorganic Hybrid Based on Hexachloroplatinate and Nitrogen Heterocyclic Cations: Their Synthesis, Characterization, Crystal Structures, and Antitumor Activities In Vitro

Three new crystal structures containing [PtCl(6)](2−), pyridinium and benzimidazole groups have been prepared: [PtCl(6)]·(H-bzm)(2)·2(H(2)O) (1), [PtCl(6)]·(H-bipy)(2)·2(H(2)O) (2), [PtCl(6)]·(H-dimethyl-bipy)(2)·2(H(2)O) (3) [H-bzm: benzimidazole cation, H-bipy: 2,2′-bipyridine cation, H-dimethyl-bipy: 4,4′-bimethyl-2,2′-bipyridine cation]. All compounds have been fully characterized by elemental analyses, single-crystal X-ray analyses, IR spectra, TG analyses, and fluorescence studies. Single-crystal X-ray diffraction analysis suggests that the primary synthon contains (+)N–H···Cl(−), including ionic bonding and hydrogen bonding interactions. The dimensions are enhanced further by secondary O–H ∙∙Cl and N–H ∙∙O hydrogen bonding interactions between donor and acceptor atoms located at the periphery of these synthons. Moreover, coulombic attractions between the ions play an important role in reinforcing the structures of these complexes. In addition, antitumor activity against human lung adenocarcinoma cell line (A549) and human nasopharyngeal carcinoma cell line (CNE-2) was performed. These complexes all showed inhibition to the two cell lines, while complex 3 exhibited higher efficiency than complexes 1–2.