Supramolecular Complexes With Polypyridine And Sulfonate Ligands: Synthesis, Crystal Structure And Properties

In this dissertation, hydrothermal/solvothermal reactions of the metal salts （Pb（II）,Zn（II）, Cd（II）, Cu（II）, Mn（II）, Co（II）, Ni（II）） with sodium1,5-naphthalenedisulfonate（1,5-NDS） and sodium2,7-naphthalenedisulfonate （2,7-NDS） as main ligands haveafforded sixteen complexes in the presence of1,10-phenanthroline （phen） and4,5-diazafluoren-9-one （dafo） as co-ligands. All complexes have been structurallyconfirmed by single-crystal X-ray diffraction. Moreover, some other characterizationmethods have been also used for complexes1-16, including elemental analysis,infrared spectra （IR） and powder X-ray diffraction （PXRD）. Thermal stability andphotoluminescence properties have been further investigated. The results are asfollows:1. Sixteen metal complexes synthesized[Pb（phen）₂（1,5-NDS）]n（1）[Zn（phen）（H₂O）₄]（1,5-NDS）·2H₂O （2）[Zn（phen）₂（1,5-NDS）（H₂O）]（3）[Cd（phen）₂（1,5-NDS）]n（4）[Mn（phen）（H₂O）₄]（1,5-NDS）·2H₂O （5）[Co（phen）₂（H₂O）（1,5-NDS）]（6）[Zn（dafo）（H₂O）₄]（1,5-NDS）·2H₂O （7）[Cd（dafo）₂（1,5-NDS）]n（8）[Cu（dafo）₂（1,5-NDS）]n（9）[Co（dafo）₂（H₂O）₂]·1,5-NDS （10）[Ni（dafo）（H₂O）₄]（1,5-NDS）·2H₂O （11）[Zn（phen）₂（2,7-NDS）（H₂O）]·2H₂O （12）[Cd（phen）₂（2,7-NDS）（H₂O）]·2H₂O （13）[Mn（phen）₂（2,7-NDS）（H₂O）]·2H₂O （14）[Co（phen）₂（2,7-NDS）（H₂O）]·2H₂O （15）[Ni（phen）₂（2,7-NDS）（H₂O）]·2H₂O （16）2. The crystal structure analysisIn the sixteen complexes,7-11are the first examples of mixed ligands, including1,5-NDS and dafo ligands. The two nitrogen atoms of a dafo ligand can coordinate tometals to form stable complexes. In addition, the oxygen atom and aromatic ring cangenerate hydrogen bonds and π-π interactions, respectively, resulting insupermolecular structures.1,5-NDS and phen ligands are used to synthesize1-6.12-16are obtained by using2,7-NDS and phen ligands. These complexes are allassembled through hydrogen bonds or/and stacking interactions between aromaticrings into multidimensional supermolecular architectures.For1,4,8and9, the [M（phen）₂]2+/[M（dafo）₂]2+units are linked by1,5-NDSligands into1D coordinated chains. In1, there are Pb-O weak bonds which increase the coordination number of Pb（II） from six to eight, resulting in the chelatingcoordination mode of two sulfonate groups. The2D supramolecular layers of1and4are all formed by stacking interactions between adjacent1D chains. Complexes8and9have similar structures. In9, dafo coordinates to Cu（II） ion as a very asymmetricbidentate ligand.8and9are expanded into3D supramolecular architectures viaintermolecular interactions （hydrogen bond and π-π interactions）.Other complexes are all mononuclear and zero-dimensional structures. In2,5,7,10and11, the uncoordinated1,5-NDS ligands play a role in balancing the charge ofthe structure. The multidimensional supermolecular aggregates were obtained bymeans of hydrogen bonds between oxygen atoms of sulfonate groups and watermoleculars. For3,6,12-16, one of six oxygen atoms in each naphthalenedisulfonateligand coordinates to metal ions to form small coordinated units. These units arestacked through hydrogen bonds between remaining oxygen atoms ofnaphthalenedisulfonate ligands and water moleculars and π-π interactions betweenaromatic rings, into the3D supramolecular aggregates, respectively.3. The thermal stabilityCoordination bonds and abundant intermolecular interactions including hydrogenbonds and π-π interactions lead to collapsing of organic framework at relative hightemperature （above300oC）. Especially, organic framework of2doesn’t collapseuntill465oC after lossing water molecules. Complexes2-16show the remarkablethermal stability, while1begins to decompose at lower temperature because of weakPb-O bonds and less intermolecular interactions.4. The solid-state photoluminescence propertiesThe photoluminescence properties of1-16and the free ligands have beenmeasured in the solid state at room temperature. For3, the emission peak at420nmmay originate from intraligand emission from the1,5-NDS ligand and shows red-shift.The maximum peaks also exhibit red-shift for6-16. The red-shift may be caused bythe reason that the organic ligand may change its energy levels between HOMO andLUMO after coordination to the metal center. In comparison with those free ligands,all complexes display enhancement of luminescent intensity because ligandscoordinate to metals to reduce the loss of energy via a radiationless pathway.Photoluminescence results indicate that these complexes exhibit goodphotoluminescent ability and are promising to have potential application value in thefield of luminescent materials.