Different Dimensions Of Eu (iii) Complexes Controlled Synthesis, Structure And Fluorescence Properties,

Considerable attentions have been paid to the rational design and synthesis of rare earth complexes in recent years,not only due to their intriguing variety of architectures and topologies but also for their potential applications as functional materials such as luminescence,catalysis and nonlinear optics.The fluorescence of Eu(â…¢) ion is well studied due to its intense,long lived excited states,its emission at long wavelengths with line-like emission bands and distinguishable long lifetimes.The appropriate ligands not only can construct the complex with novel structure,but also cause the energy transfer from ligands to Eu(â…¢) ion,resulting in good fluorescent materials.5-(2'-pyridyl)tetrazole,nicotinic acid N-oxide,2,2'-bipyridyl-3, 3'-dicarboxylic acid and oxalic acid are selected as the ligands,Eu(â…¢) ion and Ag(â… ) ion as center ions to design and synthesize four novel rare earth complexes with different structures.Characterizations for complexes 1-4 by single crystal X-ray diffraction,IR,elemental analysis,thermal analysis and fluorescence have also been described.Furthermore,we also discuss how the dimensionality of the resulting coordination frameworks and fluorescence of Europium(â…¢) complexes can be manipulated by the factors of dosage of the second ligand or adding the other metal ion.1.The optimization of synthesis condition of 5-(2'-pyridyl)tetrazole is that the molar ratio of NaN₃:2-cyanopyridine:triethylamine is 1.05:1:1.15,the reaction time is 12h,and yield of 5-(2'-pyridyl)tetrazole is increased to 78.1% based on 2-cyanopyridine.Besides,[Eu(C₆H₄N₅)₃(H₂O)₃](H₂O)_3.5(1) was prepared with 5-(2'-pyridyl)tetrazole.In complex 1,Eu(â…¢) ions are linked together by hydrogen bond to form two-demensional network structure.The complex 1 exhibits great characteristic emission of Eu(â…¢) ion.2.N-oxide nicotinic acid and oxalic acid are selected as the first ligand and the second ligand,respectively,and two Europium(â…¢) complexes[Eu₂ (NNO)₄(COO)₂(H₂O)₂](2) and Eu₂(NNO)₄(OOC-COO)(H₂O)₂(3)(HNNO= nicotinic acid N-oxide,HOOC-COOH= oxalic acid) were synthesized under hydrothermal condition.In complex 2,the Eu(â…¢) ions are linked together by carboxyl groups of NNO ligands to form an infinite one-dimensional chain, which further construct the two-dimensional supramolecular network structure with hydrogen bond.Complex 3 holds three-dimensional topological structure linked by nicotinic acid N-oxide and oxalic acid.The complex 3 exhibits great characteristic emission of Eu(â…¢) ion,which is stronger than complex 2. Furthermore,the factors of dosage of the second ligand or adding the metal ion are discussed aiming at finding out the influence in structures of complexes.3.Europium(â…¢) complex[Eu₄Ag₂(C₁₂H₆O₄N₂)₅(OH)₄(H₂O₎3]·10H₂O(4) was synthesized by 2,2'-bipyridyl-3,3'-dicarboxylic acid under hydrothermal condition with Eu₂O₃ and AgNO₃,which possess an novel three-dimensional structure.The 2,2'-bipyridyl-3,3'-dicarboxylic acid shows five coordination modes in the complex,which is rare in rare earth complex reported. Furthermore,four new coordination modes are shown in the paper.Complex 4 exhibits great characteristic emission of Eu(â…¢) ion.Besides,we also discuss the factors of mole ratio of reactants,the reaction temperature and time to determinate the optimum conditions for the resulting structure of complex 4. Meanwhile,microtube was obtained when the molar of AgNO₃ is more than 0.4 mmol.