| Coordination polymers,which are composed of organic ligands and metal ions or metal clusters through coordination bonds,are new crystalline materials with periodic structures.In order to construct coordination polymers with specific structures and properties,it is very important to select organic ligands and metal ions reasonably.In this paper,we choose the tetravalent thorium ion and organic ligands of 3,3',5,5'-tetrafluorobiphenyl-4,4'-dicarboxylic acid(H2TFBPDC)?biphenyl-4,4'-dicarb-oxylic acid(H2BDC)?1,3,5-tris(3,5-difluoro-4-carboxyphenyl)benzene(H3SFBTB),4,4'-dicarboxyl biphenyl sulfone(H2DSBPDC),azobenzene-4,4'-dicarboxylic acid(H2ADC),and 4,4'-stilbene dicarboxylic acid(H2SDC)for building thorium coordination polymers.Firstly,the compound 1 and 2 were synthesized using H2TFBPDC and thorium ion.The crystal structures,thermal stabilities,infrared spectra,powder x-ray diffraction patterns and gases adsorption properties of these two compounds were characterized,respectively.Compound 1 and 2 both are based on the hexanuclear[Th6O4(OH)4]clusters formed from six Th(IV)atoms linked by four?3-O and four?3-OH groups.In compound 1,each hexanuclear cluster is connected to twelve[Th6O4(OH)4(COO)12]through twelve TFBPDC2–ligands to yield a three-dimensional(3D)framework with the octahedral cages and the tetrahedral cages.At 298 K,the adsorption selectivities of compound 1 for the mixture of propyne/propylene with the molar ratio of 1/99 and0.1/99.9 are 2 and for the propyne/propane mixture with the molar ratio of 1/99 and0.1/99.9 are 1.49.Such gases adsorption behavior indicate that compound 1 shows the gases separation for propyne/propylene mixture and propyne/propane mixture.In addition,compound 1 exhibits the high uptake for propyne with the uptake of 8.16mmol/g,which is one of the best performance coordination polymer for adsorbing propyne.Furthermore,compound 1 shows high water stability and acid-resistant properties and is the excellent material for storage of propyne.In compound 2,each hexanuclear cluster is surrounded by eight TFBPDC2–ligands and four formate ligands.Each hexanuclear unit is linked by eight TFBPDC2–ligands to give a 2-fold interpenetrating 3D structure.The interpenetrating 3D structure makes the pore volum small,resulting in low uptake of propyne(2.07 mmol/g)for compound 2.But the adsorption selectivities of compound 2 for the propyne/propylene and propyne/propane mixtures are higher than those of compound 1,suggesting the small pores help for the gases separation.In order to study the effect of the fluorine atom on the gases adsorption of compound 1,compound 3 was synthesized based on the biphenyl-4,4'-dicarboxylate ligand,which is isostructral with compound 1.However,compound 3 shows similar uptake of propyne and adsorption selectivities of propyne/propylene and propyne/propane mixtures.Such results indicate the fluorine atoms in compound 1has small effect on the gases adsorption and seaparation.Secondly,the organic ligands of 1,3,5-tris(3,5-difluoro-4-carboxyphenyl)benzene,4,4?-dicarboxybiphenyl sulfone,azobenzene-4,4'-dicarboxylic acid,and 4,4?-stilbene dicarboxylic acid were used for construction of the thorium coordination polymers.The crystal structures,thermal stabilities,infrared spectra,powder X-ray diffraction patterns and fluorescence properties of four thorium coordination polymers have been characterized.All compounds are based on the hexanuclear[Th6O4(OH)4]clusters formed from six Th(IV)atoms linked by four?3-O and four?3-OH groups.Each hexanuclear[Th6O4(OH)4]cluster is surrounded by eight1,3,5-tris(3,5-difluoro-4-carboxyphenyl)benzene ligands and four formate ligands.The 1,3,5-tris(3,5-difluoro-4-carboxyphenyl)benzene ligands link the[Th6O4(OH)4]clusters to generate a 3D framework featuring octahedral cages and tetrakaidecahedral cages.Compound 5 has a similar structure to that of compound 1,each hexanuclear cluster is connected by twelve 4,4?-dicarboxybiphenyl sulfone ligands to give a 3D structure.The V-shaped configuration and flexibility of the 4,4?-dicarboxybiphenyl sulfone ligand make the pores of the 3D structure of commpound 5 filled by the ligand itself,leading to a nonporous structure.Compound 6 and 7 are isostructural to that of compound 1.However,the sizes of the cages in compound 6 and 7 are larger than those in compound 1,as the result of the long organic ligands.The poor qaulity of the crystals are result from the large guest solvent molecules in pores of compounds 6 and 7.Thus the pore characterization of the three compounds are not performed.Only the fluorescence properties of the two compounds have been provided. |
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