Synthesis,Characterization And Properties Of Thiazole Schiff Bases And Their Metal Complexes

In recent decades,the potential properties of Schiff bases and their complexes as medicines and new materials have attracted widespread attention in various fields.The multifunctional properties of Schiff bases are mainly attributed to the aldehydes/ketones and amines used in their condensation reactions.The molecular groups mainly include aromatic rings and heterocyclic rings.Especially for heterocyclic rings,it is more widely used and can provide many kinds of metal coordinations.The ability of coordination,especially with those bioliogically active metal ions,will greatly enhance the performance of these Schiff bases,and will expand the application field of these complexes in various aspects.The thiazole ring is a well-used five-membered heterocyclic building block.The schiff base of the thiazole ring exists in a variety of biologically active heterocycles and natural products,and is considered to be the main component of a variety of biologically active compounds.It was reported that compounds containing thiazole rings have a wide range of applications in medicine,antioxidant,catalysis,electrochemistry,optics and other aspects.In this thesis,we have synthesized eight Schiff bases based on the thiazole ring(HMTF,HMTT,HMTB,HMTI,HMTP,HMTN,HMTH,DHMT),as a continuing work of our on-going research.Since the single crystals of most new compounds were successfully cultivated,the X-ray single crystal diffraction method was used to confirm their affirmatory structures.On the basis of their crystal structures,packing structures and coordination modes have been analyzed.We have found that the ligand molecules are mainly constructured by various?···?stacking interactions.C-H···?weak interactions were also found in the crystal structure of HMTH.As for their properties,we have performed UV-Vis absorption spectrum,fluorescence performance analysis and cytotoxicity test for these eight thiazole Schiff bases.Through Quantum Chemistry calculations,the mechanism of the UV-Vis spectrum were explained.The calculations show that the UV-Vis absorption spectra of the thiazole Schiff base in the gaseous and solvent states are mainly caused by the???*electronic transition.Fluorescence test showed that the thiazole Schiff base synthesized here showed good fluorescence performance.Proliferation experiments on human malignant melanoma cells(A375),lung cancer cells(A549),and cervical cancer cells(HELA)were held by MTT methods.MTT results showed that the IC₅₀ values of most of the compounds against three cancer cells exceeded 100?M,indicating that they have mild inhibitory activities,and that further modifications are required in the future.At the same time,we also conducted a large number of coordination studies on eight thiazole Schiff bases,leading to the successful cultivation of single crystals for four metal complexes.Crystal structures show that C-H···?weak hydrogen bonds and?···?interactions play the most important role in their packing modes.Unfortunately,the yields of most complexes are so low that we cannot get enough samples for systematical research for their optical and anti-proliferation properties.Only the cytostatic activities for the silver complex were conducted.The results showed that the anti-cancer activity of the ligand can be greatly improved when forming silver complexes.