Al³⁺Ions Sensing Properties Of4-acetyl Pyrazolone Schiff-bases And Biological Activities Of Their Cu（Ⅱ）, Zn（Ⅱ）, Ni（Ⅱ）Complexes

Schiff-bases were widely used in the fields of biosensors and anticancer drugs. In this thesis, the synthesis and characterization of seven Schiff-base ligands were reported and their sensing properties were also studied. In addition, the biological activities of their transition metal complexes were investigated. The thesis can be divided into3parts:In the first part of the thesis, we have introduced the applications of heterocyclic compounds containing N atoms and their Schiff-bases and the necessarity of new sensors for Al3+ions. Furthermore, the mechanism and the current development of Al3+ions sensors have been presented. Finally, the DNA binding modes of metal complexes have been summarized.The second part of the thesis included three chapters. Firstly, two fluorescent Al3+ions chemosensor,1-phenyl-3-methyl-5-hydroxypyrazole-4-acetone-(benzoyl) hydrazone(L1) and4-(1’-phenyl-3’-methyl-5’-hydroxypyrazole)-1-acetone-(2’-hydroxybenzoyl) hydrazone (L2) were synthesized and characterized. L1and L2can detect Al3+ions sensitively in ethanol solution with the detection limit of2×10-7M and2.5×10-8M via PET progress. Secondly, another two fluorescent Al3+ions chemosensor,1-phenyl-3-methyl-5-hydroxypyrazole-4-acetone-(isonicotinoyl) hydrazone (L3) and1-phenyl-3-methyl-5-hydroxypyrazole-4-acetone-(nicotinoyl) hydrazone (L4), were synthesized. They can detect Al3+ions in ethanol solution with forming an1:1complex between L and Al3+ions, which can be certified by IR spectra, MS-ESI, Job’s-plot and the density functional theory (DFT) calculations. Finally, a novel fluorescent Al3+ions chemosensor,1-phenyl-3-methyl-5-hydroxypyrazole-4-acetone-(3’,4’-dimethylpyrrole-2’-formyl) hydrazone (L5) was synthesized and characterized. L5can detect Al3+ions in ethanol solution with a significant fluorescence enhancement of a turn-on ratio over155-fold due to the formation of an1:1complex between L5and Al3+ions and the detection limit for Al3+ions was considered to be5x10-9M in ethanol solution.In the third part of the thesis, two Schiff-base ligands and their Cu(II), Zn(Ⅱ), and Ni(Ⅱ) complexes were synthesized and characterized by1HNMR, MS, elemental analysis, single-crystal X-ray diffraction etc. The calf thymus DNA (ct DNA) binding mechanism and affinity of the free ligands and their transition metal complexes were investigated by UV/Vis spectroscopy, fluorescence titration spectroscopy, EB displacement experiments and viscosity measurements. Experimental results indicated that the free ligands and their metal complexes can bind to DNA via an intercalation mode and the metal complexes bind to DNA more strongly and deeply than the free ligands alone. In addition, their antioxidant activities were investigated by hydroxyl scavenging methods, indicating that the compounds show strong antioxidant activities.