Syntheses,Characterization And Antibacterial Activity Of Complexes Based On 6,6’-dihydroxyl-2,2’-bipyridine

In recent years,due to the using of bacteriostatic drugs,problems for enhanced resistance to pathogens have become increasingly prominent,and the demand for high-storage magnetic materials is increasing with the continuous development of technology.It has been found that some complexes have antibacterial properties,and the single-molecule magnets have high storage potential.Therefore,the synthesis of new complexes and exploration of their magnetic and bacteriostatic activities are conducive to the advancement of science technology and biomedicine.Thereinto,6’-dihydroxyl-2,2’-bipyridine（dhbpH₂）was used as ligand to synthesize 13 novel metal complexes by hydrothermal method,stirring method and solvothermal method,including 3 transition metal complexes（Cu,Ni,Mn）and two series of 3d-4f heterometallic complexes（Co₆Ln₂ and MnLn₂）in this paper.The structures of 13complexes were characterized,and their magnetic and bacteriostatic activities were studied.The specific results are as follows:1.Three 3d complexes were synthesized through dhbpH₂ as ligands,and the formulas were[Cu（OH）（dhbpH）]_n（1）,{[Ni（dhbp）（H₂O）₄]·2H₂O}（2）and{[Mn₇Cl（O）₃（OH）（dhbp）₅（dhbpH）（H₂O）]·4DMF}（3）.1 was a 1D complex based on[CuO]_n helical chain;2 was mononuclear Ni complex;3 was heptanuclear complex composed with Mn^Ⅲ and Mn^Ⅱ.Magnetic studies have shown that complex 1 has antiferromagnetic interaction.2.The octanuclear 3d-4f complexes with the formulas of{[Ln₂Co₆（O）₂（NO₃）₂（dhbp）₆（DMF）₂]·H₂O}（Ln=Gd（4）,Tb（5）,Dy（6）,Ho（7）,Er（8）,Y（9）,Eu（10））were synthesized through dhbpH₂,Ln^Ⅲ and Co^Ⅱ ions.The two asymmetric[Ln^ⅢCo₃^Ⅱ]units are composed of Ln^Ⅲ and Co^Ⅱ ions through O and N atoms.Magnetic studies have shown that there is an antiferromagnetic interaction between Co and Co in complexes 4-10,and theχ’of[Dy₂^ⅢCo₆^Ⅱ]（6）shows distinct peak,and it has slow relaxation behavior and can be used as a single molecule magnet.3.The trinuclear 3d-4f complexes with the formulas of{[Ln₂Mn（dhbpH）₆（NO₃）₂]·DMF}（Ln=Gd（11）,Dy（12）,Ho（13））were synthesized through dhbpH₂,Ln^Ⅲ and Mn^Ⅱ ions.The structure is butterfly-like composed of three metal centers as a basic skeleton.4.It was found that complexes 1-13 are superior to Gram-positive negative bacteria against Gram-negative bacteria,while the antibacterial activity of complexes 4-13 against four strains is better than complexes 1-3 through antibacterial activity research.In addition,the antibacterial activity of the complexes Co₆Ln₂ is better than that of Mn₂Ln which in the case of including the same Ln^lll ions,metal complexes containing heavy 4f ions have better bacteriostatic activity than metal complexes containing light 4f ions（in the case of including the same transition metal ions）.Complex[Y₂^ⅢCo₆^Ⅱ]（9）has the best antibacterial effect against Staphylococcus aureus,achieving moderate bacteriostatic effect.Furthermore,the minimum inhibitory concentration（MIC）and the minimum bactericidal concentration（MBC）of the complex 9 were measured,and the bacteriostatic rate of the complex 9 and the ligand against Staphylococcus aureus was measured by the turbidimetric method.