Synthesis, Strucutres And Magnetic Properties Of Complexes Supported By Hydroxy-rich Ligands

The design and synthesis of polynuclear complexes with fascinating structures andnovel properties have become a hot research topic in recent years. Among the organicligands which are usually used for building polynuclear complexes, hydroxyl-richligands are the most used ligands not only for the possibility of synthesizing polynuclearcomplexes but also for the versatility in obtaining supramolecular coordinationassemblies. This thesis manly studies the synthesis, structures and properties ofcomplexes containing hydroxyl-rich ligands. Twenty coordination complexes weresynthesized and characterized by elemental analysis, IR and X-ray single crystaldiffraction analysis. The solid luminescent properties, UV-Vis and magnetic propertiesof some of these complexes were also studied. The main results are summarized asfollows.Six polynuclear coordination complexes of the compositions [Zn(H2Shi)(OAc)]n(1),[Cd(H2Shi)2(H2O)]n(2),[MnⅢ4Dy(Shi)4][(CH3CH2)3NH](3),[MnⅢ4Gd(Shi)4][(CH3CH2)3NH](4),[MnⅢ4Sm(Shi)4][(CH3CH2)3NH](5), and[MnⅢⅡ5Mn(Shi)5Py6(CH3COO)2](6), have been solvothermally synthesized by usingsalicylhydroxamic acid as the ligand. The complexes were characterized by X-ray singlecrystal diffraction analysis, IR and elemental analysis. X-ray single crystal diffractionstudies indicated that complexes1and2display one-dimentional structure, complexes3-5are heterometallic3d-4f complexes with12-crown-4structure, while complex6is amixed-valence hexanuclear manganese compound coordinated by triple deprotonatedligands, acetate anions and pyridine molecules.Nine complexes of the formula [CoII2(HIPP)4(SO4)2](7),{[CoII3(HIPP)2(IPP)2(SO4)2(CH3OH)2] CH3OH H2O}(8),[CoII3(IPP)6](9), {[CoII4(IPP)8] H2O}(10),[CoII2(IPP)2(OAc)2]n(11),{[NiII3(HIPP)2(IPP)2(SO4)2(CH3OH)2] CH3OH H2O}(12),[Zn(HIPP)4Cl2](13),[Zn2(IPP)4](14), and [Zn4(IPP)8(EtOH)](15) based on the ligand HIPP (HIPP=2-(imidazo[1,5-a]pyridin-3-yl)phenol) were synthesized and characterized. The solidphotoluminescent properties of the ligand HIPP and complexes7,9,11,13-15havebeen studied. Variable temperature (2.0–300K) magnetic studies indicated weakantiferromagnetic couplings between the metal centers in7and11, and weakferromagnetic CoII CoIIexchange interactions in9.Five complexes of the compositions [CoII4(HL1)4](16),[ZnII4(HL1)4](17),[CuII4(HL1)4](18),[ZnII4(HL2)4](19) and [CoII4(HL2)4](20) have been synthesized byusing Schiff bases H3L1and H2L2[H3L1=1-((2-hydroxy-3-methoxybenzylidene)amino)ethane-1,2-diol, H2L2=1-((2-hydroxybenzylidene)amino)-2,3-dihydro-1H-inden-2-ol] as ligands. Complexes16-18all consist of a cubane core with the metal centers and deprotonated oxygenatoms occupying alternate vertices. Complexes19and20are also tetranuclear. The fourmetal ions in complexes19and20are located at four vertices of a defect dicubane (withtwo missing vertices) and are bridged by six deprotonated oxygen atoms.Variable-temperature magnetic susceptibilities in the temperature range2-300Kindicated ferromagnetic exchange interactions in both complexes16and18. In addition,the photoluminescent studies showed that the reactions between Schiff base ligands andd10metal ions may give us a new vision in constructing functional luminescentmaterials.