Syntheses,Structures And Proton Conduction Properties Of Rare Earth And Transition Metal Coordination Compounds Constructed By Diphenylsulfone-3,3'-disulfo-4,4'-dicarboxylate Ligand

Coordination polymers are a new type of porous crystalline materials with periodic network structure formed by organic ligands and metal ions through coordination bonds.Additionally,the selection of the organic ligands plays a vtial role for building the coordination polymers with specific structures and functionalties.Firstly,the sulfonate group with fast transport nature is incorporated into an organic ligand with carboxylate groups to give the novel ligand of diphenylsulfone-3,3'-disulfo-4,4'-dicarboxylic acid?H₄DPSDSDC?.Secondly,six compounds were synthesized from diphenylsulfone-3,3'-disulfo-4,4'-dicarboxylate ligand and rare earth ions.Compounds?1???6?are isomorphous.The carboxylate groups bridge the rare earth metal ions to generate one-dimensional chains,which are linked by the DPSDSDC^4–ligands to form a three-dimensional framework.The compound Tb?6?was selected for testing the proton conduction.At 85?and 95%relative humidity,the proton conductivity of compound Tb?6?is 7.8171×10^-5 S cm^-1.Moreover,the solid state excitation and emission spectra of the compound Eu?4?and Tb?6?at room temperature were tested.The compound Tb?6?serves as a potential luminescent sensor for sensing of uranyl ion.Finally,compounds?7???10?were constructed of diphenylsulfone-3,3'-disulfo-4,4'-dicarboxylate ligands and transition metal ions.Compounds?7?and?8?are two-dimensional layered structures.The mononuclear Zn?H₂O?₄ units in compound?7?are connected by DPSDSDC^4–ligands to give a one-dimensional chain,which is linked by the K?O bonds associated with sulfonate oxygen atoms and bridging water oxygen atoms to form a two-dimensional layer.The two-dimensional layers are linked by the hydrogen bonds to provide a three-dimensional supramolecular framework.In compound?8?,the tetranuclear Cu₄??₃-OH?₂ clusters are bridged by the hydroxyl groups to give one-dimensional chain,which is connected by DPSDSDC^4–ligands to generate a two-dimensional layer.The two-dimensional layers in compound?8?are further linked by interlayered hydrogen bonds associated with the lattice water molecules to form a three-dimensional supramolecular framework.At 85?and 95%relative humidity,compounds?7?and?8?show the highest conductivities are1.5759×10^-4 S cm^-1 and 5.3252×10^-5 S cm^-1,respectively.The infinite well-defined hydrogen-bonding networks in compounds?7?and?8?facilitate the fast proton transport,which are responsible for the high proton conductivities for compounds?7?and?8?.Thus the atomically precise determination of the proton transport pathways for both compounds is achieved.Such insights on proton-conducting mechanism are highly desirable for developing of novel proton-conducting materials.Compound?9?has a three-dimensional structure wherein the DPSDSDC^4–ligands and 4,4'-bipyridine ligands linked the copper ions.At 85? and 98%relative humidity,the proton conductivity of compound?9?is 9.4734×10^-6 S cm^-1.The presence of the hydrophobic4,4'-bipyridine ligands may be responsible for the low proton conductivity.In compound?10?,the carboxylate groups bridge cobalt ions to form one-dimensional chain.The adjacent one-dimensional chains are linked by DPSDSDC^4–ligands to form a two-dimensional layered structure.At 85?and 95%relative humidity,the proton conductivity of compound?10?is 5.2266×10^-5 S cm^-1.