| In molecular magnetic materials,complexes with spin crossover(SCO)properties and single molecular magnet(SMM)behavior exhibit reversible magnetic bistability,which has potential applications in the fields of molecular switches,data storage and display materials.In this thesis,13 transition metal complexes of iron,cobalt and manganese with novel structures were synthesized with H3ATD and H3ADNA as main ligands.The structures and magnetic properties of these complexes were discussed.The specific research is as follows:1.two ion pair complexes[PPh4][Fe III(H3TAD)2]·3H2O(1)and[Fe II(phen)3][Fe III(H3TAD)2]·3DMA.3.5H2O(2)(phen=1,10-phenanthroline,DMA=N,N-Dimethylacetamide)and three neutral linear trinuclear complexes[Fe IIFe 2III(H3TAD)4(H2O)4]·4DMA·3H2O(3),[Cd IIFe 2III(H3TAD)4(H2O)4]·4DMA·3H2O(4)and[Fe IIFe 2III(H3TAD)4(DMF)2(H2O)2]·2DMF·2H2O(5)(DMF=N,N-dimethylformamide)were constructed with H3ATD and iron ion.Magnetic measurements show that 1 maintains low spin state in the temperature range of 2-500 K,while 2,3,4 and 5 exhibit different high-temperature spin crossover behavior.2.two Co III-Co II-Co IIIlinear mixed valence trinuclear complexes[Co IICo 2III(HATD)4(H2O)4]·4DMA·3H2O(6)and[Co IICo 2III(HATD)4(DMF)2(H2O)2]·2DMF·2H2O(7)were synthesized by the reaction of H3ATD and Co(II)by adjusting the solvent of DMA and DMF.Two gird like mixed valence tetranuclearionpaircomplexes[Co 2IICo 2III(HATD)4(bpp)2(H2O)2][Co III(HATD)2]2·8DMF·6H2O(8)and[Co 2IICo 2III(HATD)4(bpp)2(H2O)2][Co III(HATD)2]2·8DMSO·4Me OH(9)(DMSO=dimethyl sulfoxide)were synthesized by the reaction of tridentate chelating ligand 2,6-bis(1-pyrazolyl)pyridine(bpp)with complex 6/7.Magnetic measurements show that complex 6-9 exhibits slow relaxation behavior in the external field.Two ion pair complexes[Co III(HATD)2]2[Co II(phen)3]·3DMA·3.5H2O(10)and[Co III(HATD)2]2[Co II(terpy)2]·4DMA·0.5H2O(11)were synthesized by the reaction of strong chelating ligands phen and terpy with 6/7,respectively.Magnetic measurements show that Co(II)in 10 is high spin and exhibits slow relaxation behavior in the external field,while Co(II)in 11 does not exhibit slow relaxation behavior in the zero field and external field,but display spin crossover behavior.3.two 1D chain complexes of{[Mn3(HADNA)2(DMF)2(H2O)2]·0.5DMF·0.5H2O}n(12)and{Mn6(HADNA)4(H2O)10]·8DMSO·2.5H2O}n(13)were synthesized by self-assembly of H3ADNA with transition metal Mn(II)in DMF and DMSO,respectively.The magnetic properties of complexes 12 and 13 have been studied.It is found that there is a weak antiferromagnetic interaction.No AC susceptibility signals were observed above 1.8 K in zero field and external field,indicating that complexes 12 and 13 do not exhibit slow relaxation. |
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