Study On The Substitution Effects Of Zinc Terpyridine Complexes On Photoluminescence,Antiproliferative Potential And DNA Binding Properties

In recent years,terpyridine metal complexes are attracting increasing attention due to their interesting properties in anticancer and other fields.In order to explore the effect of substituents on antiproliferative potential and DNA binding ability,a series of 4'-phenyl-terpyridine ligands based on different types and positions of substituents were prepared and 9 zinc complexes of these ligands were synthesized and characterized by FT-IR,¹H NMR,elemental analysis and X-ray single crystal diffraction.The main research contents of this article are as follows:Using zinc benzoate to react with six terpyridine derivatives ligands,six zinc benzoate terpyridine complexes were synthesized by organic solvent method under room temperature.The central Zn???ions of complexes are coordinated with three N atoms at terpyridine and oxygen at benzoate in a five-coordinated triangular bipyramidal geometry.All the six complexes have strong fluorescence emission peaks in high-energy region,which infers that they are generated by the?-?*energy level transition on the aromatic ring,while the peaks of some complexes in low-energy region illustrate that they are caused by the electronic transfer between zinc ion and the ligand.Three human cancer cell lines were used for antiproliferative potential of the complexes:human lung cancer cell line?A549?,human esophageal cancer cell line?Eca-109?and human breast cancer cell line?MCF-7?.The results indicate that the complexes have good effects on these cancer cells with the IC₅₀ values between 0.240–3.792?M,which are better than that of cisplatin,which is commonly used as clinical drug.The DNA binding ability of the complexes was studied by UV-vis spectroscopy and fluorescence titration,while the interaction between the complexes and CT-DNA,AT6,GC6 short-chain DNA fragments and G-quadruplex were analyzed by circular dichroism?CD?.Molecular docking software was used to found that these complexes can bind to DNA and the main binding mode is intercalator.Three terpyridine ligands with different hydroxyl substituent positions were prepared.Three zinc propionate terpyridine complexes were synthesized by reaction of the three ligands and zinc propionate.The central Zn???ions of the complexes are coordinated with three N atoms at the ligands and two O atoms at the propionate groups in a five-coordinate triangular bipyramid geometry.The solid fluorescent properties of the complexes were determined.It is found that the overall structures of the complexes are similar,which means the change of the substitution position of the hydroxyl substituent at the 4'-phenyl group may not have significant effects on the fluorescent properties of the complexes.The antiproliferative properties of the three complexes were studied by cell experiment with human lung cancer cell line?A549?,human liver cancer cell line?Bel-7042?and human breast cancer cell line?MCF-7?.The test results show that the three zinc propionate complexes have good abilities to inhibit the proliferation of the three cancer cells with the IC₅₀ values between 0.198–3.409?M.Using UV-vis,circular dichroism,gel electrophoresis and molecular docking to investigate binding properties between the three complexes and DNA.In DNA binding experiment,it is found that the three complexes can be bound very tightly with DNA mainly in an embedded combination mode,and such mode can induce the cleavage of the circular DNA under the appropriate irradiation of ultraviolet rays.