Carboxylato-O and Pyridyl-N Hybrid Bridging Zn(II)-Based Two-Dimensional Fluorescent Coordination Polymers as Anticancer Drugs

Zinc is the second most prevalent biometal found in the human body. Zn-based polymers have been gaining attention as anticancer drugs without interfering with the normal activites of cell lines. With this importance, we have synthesized Zn(II)-based 2D heterobridging coordination polymers, {[Zn(tdc)(bpms)(H₂O)]_n, (CP-1S)} and {[Zn(tdc)(bpds)(H₂O)·2H₂O]_n, (CP-2S)} (tdc^2–, 2,5-thiophene dicarboxylate; bpms, 4,4’-dipyridyl sulfide; and bpds, 4,4’-dipyridyl disulfide). The structures demonstrate that tdc^2– bridges through monodentate coordination of carboxylate-O and (O, O)-chelation to neighboring Zn(II) centers to constitute the coordination polymer; bpms/bpds act as pyridyl-N connecting ligands and propagate almost perpendicular to the previous chain and design the 2D CPs. The materials emit in the blue region with fluorescence lifetimes of 6.08 ns (CP-1S) and 5.41 ns (CP-2S). The antiproliferative and apoptotic efficacies of the CPs have been studied in the presence of four cancer cell lines (human breast cancer cells (MCF-7), human prostate cancer cells (PC-3), lung carcinoma epithelial cells (A549), and triple-negative breast cancer cells (MDA-MB-231)) and have been compared with the standard anticancer drug, i.e., cisplatin. The CPs are not cytotoxic to the human fetal lung fibroblast cell line (WI-38), and the highest anticancer efficiency is observed against MCF-7 (IC₅₀: 14.62 ± 1.49 (CP-1S) and 24.39 ± 1.23 μM (CP-2S) with reference to cisplatin (IC₅₀, 6 μM). This study has a great deal of potential for the development of pharmaceuticals and provides an overview of the use of coordination polymers for medicinal purposes.