Synthesis,Magnetic Performance Of Transition Metal Complexes Based On Aromatic Heterocyclic Ligands

Heteroaromatic compounds and their transition metal complexes which provided novel structures and unique performance attract widespread attentions in the field of coordination chemistry, materials science and biomedicine and have been deeply studied in recent years. The properties of coordination polymers are determined by their structures. Therefore, the influence of different factors on the molecular form and accumulation mode in the solid state has also become the focus and hot topics in the field of crystal engineering. Synthesis of transition metal complexes with derivatives of 2,2’-pyridine, N,O-chelate heterocyclic carboxylic acid compounds and derivatives of 1,2,4-triazole is the main work of this thesis. In order to study the influence of different anions, solvent H2O molecule, different metal ions and substituents on the structures and properties of complexes, the X-ray single crystal structures, Hirshfeld surface, magnetism, optical properties and thermal performance have been analyzed. The main contents of this thesis as follows:1. We obtained four single crystals of complexes which derived from different ferrous salts and 4,4’-dimethyl-2,2’-bipyridine, respectively, [Fe(dmbpy)3](ClO4)(SeCN) (1), [Fe(dmbpy)3](ClO4)(SCN) (2), [Fe(dmbpy)3](Fe2OCl6) (3) and [Fe(dmbpy)3](BF4)2 (4). The effects of different anions on their structures, accumulation modes, magnetic properties and thermal stability were analyzed in detail.2. Two single crystals of complexes were synthesized, named [Cu(L1)2(H2O)2]·2H2O (5) and [Co(L2)2(H2O)4]·4H2O (6), which derived from CuSO4·5H2O and CoCl2·6H2O with 1-methyl-3-imidazole-4-carboxylic acid and 2-methyl-5-pyridine carboxylic acid, respectively. The important role of coordination H2O molecules and lattice H2O molecules in the construction of crystal structures were analyzed. In addition, the thermal stability and fluorescence properties were investigated.3. Four single crystals of complexes were obtained, respectively, [Co(dmbpy)2(dca)2]·CH3OH (7), [Ni(dmbpy)2(dca)2]·CH3OH (8), [Zn(dmbpy)2(dca)2] (9) and [Cu(dmbpy)2(OH)2]·5H2O (10), which derived from 4,4’-dimethyl-2,2’-bipyridine and N(CN)2- anions with different transition metal ions. The effect of different metal ions on the crystal structures were discussed, and the UV spectra of 4,4’-dimethyl-2,2’-bipyridine as four complexes were analyzed.4. The ligands of hydroxyl and methoxy substituted 1,2,4-triazole which derived from 4-amino-1,2,4-triazole were designed and synthesized, marked as 4-h-batz and 3-h-4-m-batz. Through molecular self-assembly, two kinds of 1D coordination polymers were obtained with Fe(BF4)2-4H2O, respectively, [Fe(4-h-batz)3(BF4)2]n (11) and [Fe(3-h-4-m-batz)3(BF4)2]n (12). The UV spectra of the ligands and coordination polymers were analyzed, and the spin transition properties of the coordination polymers were also studied.