Syntheses,Structures And Properties Of Metal-Organic Framework Constructed By Carboxylic Ligands Containing Hydrophilic Sulfonate Groups

Metal-organic Framework（MOF）is a new type of crystalline material developed in later 20 century.MOF has the periodic and diverse structures,mild preparation conditions and structural designability.MOF acting as functional materials have potential applications in gas storage and separation,catalysis,proton conduction,second-order nonlinearity,fluorescence,magnetism.A large amount of MOFs with diverse structural topology can be constructed by using different ligands.Nove ligands with different functional groups can be used for construction of MOFs with diverse structures and interesting physical properties.In order to obtain the MOFs with high proton conduction,two sulfonate-carboxylate ligands（biphenyl-3,3’-disulfonyl-4,4’-dicarboxylicacid（H₄BPDSDC）and benzophenone-3,3’-disulfonyl-4,4’-dicarboxylic acid（H₄BODSDC））were synthesized in our group.The highly hydrophilic sulfonate group exhibits weak bind ability to the metal centers in MOFs,but shows a fast proton transfer.The carboxylate group of the organic ligand can form the strong coordination bonds with the metal ions in the MOFs,thus giving the robust MOFs.In this thesis,MOFs based on the two sulfonate-carboxylate ligands were isolated.The auxiliary N-containing ligands were introduced into the metal-sulfonate-carboxylate system for construction of more stable MOFs.The proton conductivities of these MOFs were investigated in detail.Some MOFs exhibit high proton conductivity.The luminescent properties of some compounds also studied.The lanthanide compounds based on the biphenyl-3,3’-disulfonyl-4,4’-dicarboxylic ligand show a potential for sensing temperature.The formulas of these compounds in this paper are listed following.（1）[Co（BPDSDC）_0.5（4,4’-bpy）_0.5（H₂O）₂]_n（2）{[Co（BPDSDC）（H-4,4’-bpy）₂]·6（H₂O）}_n（3）{[Cd（BPDSDC）_0.5（2,2’-bpy）₂]·（H₂O）}_n（4）{[Cd（BPDSDC）_0.5（2,2’-bpy）（H₂O）]·（H₂O）}_n（5）{[Tb₂（BPDSDC）（BDC）（H₂O）₆]·4H₂O}_n（6）{[Eu₂（BPDSDC）（BDC）（H₂O）₆]·4H₂O}_n（7）{[Mg₂（BODSDC）（H₂O）₆]·4（H₂O）}_n（8）{[Zn₅（BODSDC）₂（ac）₂（bpe）₃（H₂O）₄]·4（H₂O）}_n（9）{（H₃O）₂[Zn₅（BODSDC）₂（μ₃-OH）₂（μ₂-OH）₂（bpe）₂（H₂O）₄]}_n（10）{[Zn（BODSDC）_0.5（bpe）（H₂O）₂]·（CH₃CN）}_n（11）{[Co（BODSDC）_0.5（bpe）（H₂O）₂]·（CH₃CN）}_n（H₄BPDSDC:biphenyl-3,3’-disulfonyl-4,4’-dicarboxylic acid;4,4’-bpy:4,4’-bipyridine;2,2’-bpy:2,2’-bipyridine;bpe:1,2-bis（4-pyridyl）ethylene;H₄BODSDC:benzophenone-3,3’-disulfonyl-4,4’-dicarboxylic acid;Hac:acetic acid）This paper is divided into the following four parts:The first chapter mainly introduces the concept of metal-organic framework and the application and research progress of MOFs in fluorescence,proton conduction and gas adsorption/separation.The main idea and significance for this paper is also described here.Six compounds based on the biphenyl-3,3’-disulfonyl-4,4’-dicarboxylic ligand including four transition metal-based compounds and two lanthanide-based compounds were described in chapter two.In compound 1,the carboxylate oxygen atoms link two Co（II）into a dinuclear unit,which is bridged by the biphenyl-3,3’-disulfonyl-4,4’-dicarboxylic and 4,4’-bipyridine ligands to form a two-dimensional（2D）layer.Compound 2 can be isolated by altering the reaction condition for synthesis of compound 1.The single Co（II）ions are connected by the biphenyl-3,3’-disulfonyl-4,4’-dicarboxylic ligands to give a one-dimensional（1D）chain.The 4,4’-bipyridine ligand serving as the terminate ligand monodentately coordinates to the Co（II）ion.The uncoordinated sulfonate oxygen atoms are arranged at the edges of the 2D layer or 1D chain in the Co（II）compounds.As a result,the two compounds show good proton conduction.Compound 2 shows the higest proton conductivity of 1.25×10^-3 S cm^-1under 95 RH and 358 K.The compound 3 and 4 are Cd（II）compounds with the auxiliary 2,2’-bipyridine ligand.The dinuclear Cd（II）units are bridged by the biphenyl-3,3’-disulfonyl-4,4’-dicarboxylic ligands to give a 1D chain.When less amount of the 2,2’-bipyridine is used in preparation of compound 3,compound 4 was obtained.The single Cd（II）ions are connected by the biphenyl-3,3’-disulfonyl-4,4’-dicarboxylic ligands to generate a1D band.In the two compounds,the 2,2’-bipyridine occupy the coordination sites of the Cd（II）ions and the sulfonate oxygen atoms are separated far away,which leads to the low-performance for the two compounds.Compound 5 and 6 are isostructural lanthanide compounds.They contain two kinds of secondary building units.One is the 2D square with nanosized grids extending to ab plane formed by 1,4-benzenedicarboxylate bridging the dinuclear lanthanide units.The other is the 1D double chain running along c axis formed from the biphenyl-3,3’-disulfonyl-4,4’-dicarboxylic ligands bridging the lanthanide ions.Each double chains are threaded through the 2D squares through the Tb-O coordination bonds to give a 3D architecture.The proton conduction and luminescent properties of the lanthanide compounds were studied.The two compounds have the potential for sensing temperature.Chapter three describes five compounds based on the benzophenone-3,3’-disulfonyl-4,4’-dicarboxylic ligand.Compound 7 is a 2D layered structure constructed from the Mg（II）ions bridged by the benzophenone-3,3’-disulfonyl-4,4’-dicarboxylic ligands.The 1,2-bis（4-pyridyl）ethylene ligand is introduced into the Zn（II）-benzophenone-3,3’-disulfonyl-4,4’-dicarboxylic system,compound 8-10 were obtained.Compound 11 is isostructural with compound 10 with the Zn（II）center displaced by Co（II）center.The Zn（II）ions are bridged by the benzophenone-3,3’-disulfonyl-4,4’-dicarboxylic and 1,2-bis（4-pyridyl）ethylene ligands to give 2D layer in compound 8.While compound 9 contains the 1D hydroxyl-bridged Zn（II）chains.The1D hydroxyl-bridged Zn（II）chains are further linked by the benzophenone-3,3’-disulfonyl-4,4’-dicarboxylic and 1,2-bis（4-pyridyl）ethylene ligands to give 3D structure.Compound 10 and 11 are 3D structure wherein two metal ions are linked by the carboxylate groups to give a dinuclear unit.The dinuclear units are bridged by the benzophenone-3,3’-disulfonyl-4,4’-dicarboxylicand1,2-bis（4-pyridyl）ethylene ligands to form a 3D structure.These compounds exhibit the proton conduction with the cooperative proton transfer of the sulfonate oxygen atoms,coordinated water molecules and solvent molecules.The fourth chapter summarizes and prospects the work of this paper.