Studies Of Functional Complexes Based On Polydentate Schiff Base Ligands And Transition Metal Ions

It is a common method to design and assemble complexes with specific functions through the selection of synthesis conditions and raw materials.Based on different organic ligands and metal ions,we can design and synthesize complexes with various properties,which have good application prospects in inorganic chemistry,analytical chemistry,electrochemistry,pharmaceutical chemistry,organic chemistry and many other fields.In this paper,two polydentate Schiff base ligands,N,N'-bis(3,5-di-tert-butyl-2-hydroxybenzyl)-1,7-diamino-4-azaheptane(H₂L),N-(8-quinolinyl)salicylaldehyde(Hqsal),and 2,2-bpy ligands,were selected to combine with transition metal ions.A variety of transition metal complexes and complex inorganic hybrid compounds with excellent properties were synthesized by solution method and hydrothermal method,Their electrical,magnetic and optical properties were studied.The paper can be divided into four chapters.The first chapter is the introduction,which summarizes the development of coordination compounds,the application of Schiff base metal organic complexes and lead halide perovskite,as well as the basis,research methods and main achievements of this paper.In the second chapter,complexes 1-3 were synthesized by using ligand H₂L and Ni,Cu,Zn transition metal ions.The molecular formulas of complexes 1-3 are:[Ni(L)]·CH₃OH(1),[Cu(L)]·CH₂Cl₂(2),[Zn(L)](3),and the metal ions are all five coordinated.Complexes 1 and2 showed good photocatalytic and electrocatalytic properties for proton hydrogen production.Both complexes and organic photosensitizers could successfully construct visible light driven her system without precious metals.Copper based complex 2 showed better catalytic activity than nickel based complex 1 in both electric and light environments.In the third chapter,using the Schiff base Hqsal as the main ligand,two similar complexes 4 and 5 were synthesized under different synthetic conditions by introducing transition metal Fe^IIIion and combining lead iodide anion.Their molecular formulas are:[Fe(qsal)₂]Pb I₃(4),[Fe(qsal)₂]Pb I₃·2DMF(5).The magnetic study shows that complex 4exhibits spin crossover behavior,and the transition temperature T_1/2?=332 K.However,the Fe ^IIIion of complex 5 maintains a high spin state throughout the temperature range,and does not exhibit spin crossover behavior.The detailed structural comparison shows that the different spatial stacking patterns of the cation chains of the two complexes,the different solvent molecules and supramolecular interactions lead to their different.In Chapter 4,we synthesized different complexes with 2,2-bpy ligands and transition metal ions Fe^II,Co^IIand Ru^IIrespectively,and introduced Pb X_nchain(X=I or Br)as the anionic part.Finally,we obtained five novel complexes,their molecular formulas are:[Fe(2,2-bpy)₃]Pb_2.75I_7.5(6),[Fe(2,2-bpy)₃]Pb₂Br₆(7),[Co(2,2-bpy)₃]Pb_2.75I_7.5(8),[Ru(2,2-bpy)₃]Pb_2.75I_7.5(9),[Ru(2,2-bpy)₃]Pb Br₄·0.5H₂O(10).The fluorescence properties showed that these novel hybrid compounds could combine the different fluorescence activities of complex cation and lead halide anion.