Syntheses,Structures And Properties Of 3d-4f Complexes Based On Salicylhydroxamic Acid

Hydroxamic acids ligands contain multiple N,O donor coordination atoms,which are easily coordinated with transition metals and rare earth metal ions to form stable metal complexes,some of them are metallacrowns.It is found that such metal complexes have attracted extensive chemists’ attention due to their unique optical properties,biological activities and magnetic properties in sensors,anticancer drugs and magnetic materials.Some 3d-4f mixed metal complexes show single-molecule magnets behaviour,therefore,we selected salicylhydroxamic acid as a ligand to react with different metal salts to obtain 20 metal complexes,including 13 metallacrowns.Their structures were characterized by X-ray single crystal diffraction,IR spectra and elemental analysis.The magnetic and optical properties of some complexes were also determined.The main sections of this thesis are as follows:1.Seven complexes were obtained through one-pot reactions with H3shi,Zn(NO3)2.6H2O and Ln(NO3)3·6H2O as reagents:(CSH6N)[PrZn(Hshi)(PhCOO)3(NO3)(Py)2](1),(C5H6N)[NdZn(Hshi)(PhCOO)3(NO3)(Py)2](2),(CSH6N)[SmZn(Hshi)(PhCOO)3(NO3)(Py)2](3),(CSH6N)[EuZn(Hshi)(PhCOO)3(NO3)(Py)2](4),(CSH6N)[TbZn(Hshi)(PhCOO)3(NO3)(Py)2](5),(C5H6N)[ErZn(Hshi)(PhCOO)3(NO3)(Py)](6),(C5H6N)[YZn(Hshi)(PhCOO)3(NO3)(Py)](7).Their structures were characterized by X-ray single crystal diffraction,IR spectra and elemental analysis.Complexes 1-5 are binuclear metal complexes with similar structure,while,the structures of complexes 6 and 7 are similar.The overall molecular framework is negatively monovalent.The free pyridinium cation neutralizes the negative charge and makes the complex presenting electrically neutral.The magnetic properties show that antiferromagnetic coupling between metal ions in complexes 5 and 6 and exhibit single-molecule magnet behaviour.The solid state fluorescence of complex 5 emits the characteristic peak of Tb3+ ions.2.Six complexes were obtained by copper metal salts and rare-earth salts:{[Cu5(shi)4][Cu4La-(shi)4(DMF)8(H2O)2]}·2DMF(8),{[Cu5(shi)4][Cu4Pr2(shi)4(DMF)8(H2O)2]}·2DMF(9),{[Cu5(shi)4][Cu4Nd2(shi)4(DMF)8(H2O)2]}·2DMF(10),{[Cu5(shi)4][Cu4Sm2(shi)4(DMF)8(H2O)2]}(11),{[Cu5(shi)4][Cu4Eu2(shi)4(DMF)8(H2O)2]}· 2DMF(12),{[Cu5(shi)4][Cu4Gd2(shi)4(DMF)8(H2O)2]}(13).Their structures were characterized by X-ray single crystal diffraction,IR spectra and elemental analysis.Complexes 8-13 contain two independent 12-MC-4 units.One metallacrown unit consists of four copper ions and four salicylhydroxamic acid ligands,the other framework of the metallacrown is similar to the former,except that four ring oxygen atoms bridge two Ln3+ ions in the cavity.The magnetic data of complexes 8,9 and 13 show that antiferromagnetic coupling between metal ions.3.Seven complexes were obtained by iron metal salts and rare-earth salts:(C5H6N)[PrFe4(shi)4(C6H5COO)4(Py)4]·.5Py(14),(C5H6N)[NdFe4(shi)4(C6H5COO)4(Py)4]·3.5Py(15),(C5H6N)[SmFe4(shi)4(C6H5COO)4(Py)4]·3.5Py(16),(C5H6N)[EuFe4(shi)4(C6H5COO)4(Py)4]·3.5Py(17),(C5H6N)[GdFe4(shi)4(C6H5COO)4(Py)4]·3.5Py(18),(C5H6N)[TbFe4(shi)4(C6H5COO)4(Py)4]·3.5Py(19),(C5H6N)[DyFe4(shi)4(C6H5COO)4(Py)4]·3.5Py(20).Their structures were characterized by X-ray single crystal diffraction,IR spectra and elemental analysis.Complexes 14-20 are 12-MC-4 metallacrowns with similar structure.The negative charge of the 12-MC-4 metallacrown is balanced by one pyridinium cation,which forms the hydrogen bond with an adjacent solvent pyridine molecule.Magnetic measurements demonstrate antiferromagnetic coupling interactions and field-induced slow magnetic relaxation in complexes 18-20.