Synthesis,Characterization,and Properties Of Complexes Based On 1,10-phenanthroline

With the development of scientific research,the study of coordination chemistry has shifted from the study of structure to the study of properties of complexes,such as magnetic properties,electrochemical properties,optical properties and so on.Therefore,it is of great significance to design and synthesize complexes with specific properties by combining structure and properties when designing complexes.1,10-phenanthroline is a classical chelated bidentate ligand.As a large conjugated system of nitrogen,it is able to coordinate with metal ions to form relatively stable complexes.At the same time,the derivatives synthesized with 1,10-phenanthroline as the basic framework are excellentπelectron acceptors,which are widely used in photochemical catalysis,electrochemical analysis,biomedicine and so on.In addition,Fe ^Ⅱion is a transition metal ion with d⁶electron configuration,and the Fe^Ⅱcomplexes are also relatively stable.Therefore,in this paper,1,10-phenanthroline was uesd as the framework to prepare derivative ligands,which were modified by hydroxyl groups and halogen atoms,then nine Fe ^Ⅱcomplexes were synthesized by solvothermal synthesis.The exact structures of the complexes were determined by infrared spectroscopy and X-ray single crystal diffraction,and then the magnetism or electrochemical properties of the nine complexes were further studied.The main work carried out in this paper includes:1.Three dichloro bridging binuclear Fe^Ⅱcomplexes Fe₂L₂Cl₂(L1=2-（2,11b-dihydro-1H-imidazo[4,5-f][1,10]phenanthrolin-2-yl）phenol,L2=3-（2,11b-dihydro-1H-imidazo[4,5-f][1,10]phenanthrolin-2-yl）phenol,L3=4-（2,11b-dihydro-1H-imidazo[4,5-f][1,10]phenanthr-olin-2-yl）phenol of 1,10-phenanthroline derivatives modified by hydroxyl were designed and synthesized,the magnetic properties of complexes were also determined.Due to the different positions of hydroxyl groups at the distal end,the complexes exhibit different magnetic properties:there is a ferromagnetic coupling between the two Fe^Ⅱions in complex1 and complex 3,but there is an antiferromagnetic coupling in complex 2.2.Cl and Br were introduced into the distal substitution sites of 1,10-phenanthroline derivatives,respectively.Two cases of Fe ^Ⅱspin-crossover complexes Fe L₂（NCS）₂（L4=2-（2-chlorophenyl）-2,11b-dihydro-1H-imidazo[4,5-f][1,10]phenanthroline,L5=2-（2-b-romophenyl）-2,11b-dihydro-1H-imidazo[4,5-f][1,10]phenanthroline）were designed and synthesized.According to the magnetic test,complexes show different spin crossover temperatures according to the different substituents.3.Halogen modified 1,10-phenanthroline derivatives were designed and synthesized,and four triligand complexes[Fe L₃]²⁺（L6=2-（2-fluorophenyl）-2,11b-dihydro-1H-imidazo[4,5-f][1,10]phenanthroline,L7=2-（4-chlorophenyl）-2,11b-dihydro-1H-imidazo[4,5-f][1,10]phenanthroline,L8=2-（4-bromophenyl）-2,11b-dihydro-1H-imidazo[4,5-f][1,10]phenanthro-line,L9=2-（4-iodophenyl）-2,11b-dihydro-1H-imidazo[4,5-f][1,10]phenanthroline）were synthesized.The electrochemical behavior of complexes 6,7 and 8 were studied by cyclic voltammetry.It was found that there was no typical redox peak of Fe^Ⅲ/Fe^Ⅱon the cyclic voltammetry curve,and it was inferred that different substitution positions play an obvious role in the redox process of complexes.