Synthesis And Luminescent Properties Of Two Types Of Semi-Rigid Substituted Benzoate-Based Rare Earth Coordination Polymers

In this paper,seven new lanthanide-organic coordination polymers were synthesized by the reactions of lanthanide salts with two types of semi-rigid main ligands 3-bromo-5-（3-carboxyphenyl）pyridine and 4,4’-oxybis（benzoic acid）,respectively.Their luminescent properties were studied.（1）Under hydrothermal condition,one coordination polymer with a one-dimensional structure was synthesized by the reaciton of La Cl₃·6H₂O,3-bromo-5-（3-carboxyphenyl）pyridine（HL）,and Na OH in a certain proportion.Its molecular formula was determined as La L₃（H₂O）₂（1）by single-crystal X-ray diffraction analysis.In complex 1,the L ligands bridge the La（III）ions to yield a one-dimensional chain-shaped structure,and the adjacent one-dimensional chains are extended to a three-dimensional supramolecular structure by the hydrogen bonding andπ?πinteractions.Complex 1 shows the photoluminescence of ligand L.（2）Using one-pot hydrothermal method,six coordination polymers with three-dimensional and one-dimensional structures were synthesized by the reactions of oxalic acid（H₂ox）,o-phenanthroline（phen）,4,4’-oxybis（benzoic acid）（H₂oba）,Ln（NO₃）₃·6H₂O（Ln=Sm,Tb,or Dy）,and Na OH in a certain proportion.Their molecular formulas were determined as Ln Na（oba）（ox）（H₂O）[Ln=Sm（2）,Tb（3）,and Dy（4）]and Ln（oba）（Hoba）（phen）[Ln=Sm（5）,Tb（6）,and Dy（7）],respectively,by single-crystal X-ray diffraction analyses.In complexes 2-4,two types of metal ions are bridged by the ox ligands to form a two-dimensional layer structure,which is extended into a three-dimensional network structure by the oba ligands as pillars.In complexes 5-7,the lanthanide ions are linked by the oba liands into a one-dimensional chain structure,and the adjacent one-dimensional chains are extended into a two-dimensional supramolecular layer by the hydrogen bonding interactions.Complexes 2-7 exhibit the characteristic luminescence of lanthanide ions,respectively.