Bifunctional tetrazole–carboxylate ligand based Zn(ii) complexes: synthesis and their excellent potential anticancer properties

Abstract

Transition metal coordination complexes have provided cancer treatment with new insights to overcome the limitations of current chemotherapeutic agents. Utilization of bifunctional tetrazole–carboxylate ligands with Zn(II) obtained two self-assembled complexes [Zn(HL¹)(bipy)_3/2(H₂O)]·CH₃OH·4(H₂O) (1) (H₃L¹ = 1,3,5-tri(2-carboxymethyltetrazol-5-yl) benzene) and [Zn(L²)₂(H₂O)₂]₂·2H₂O (2) (HL² = (5-pyridin-3-yl-tetrazol-2-yl)-acetic acid). The X-ray diffraction results showed that the two complexes displayed a two-dimensional (2D) layer structure and a one-dimensional (1D) layer structure. Nanocoprecipitation with DSPE-PEG-2000 resulted in the formation of complex nanoparticles (NPS) with excellent water dispersion. In vitro CCK-8 assay indicated the two NPs exert high cytotoxicity and sensitivity and a low half-maximum inhibitory concentration (IC₅₀) towards HeLa than HepG2 cells. In addition, the cytotoxicity was also confirmed by live/dead co-stained experiments. The presented experimental results showed the 1 and 2 NPs were capable of inhibiting cell proliferation in vitro and may help design coordination complex-based anticancer candidates for cancer cells.