Two novel ligands named 4-styrylpyridine-2,6-dicarboxylic acid (4-SPDA) and 4-(4-(2-(2, 6-dicarboxypyridin-4-yl)- vinyl)styryl)pyridine-2,6-dicarboxylic acid(DSPDA) and their complexes with Tb(Ⅲ) were synthesized and characterized by infrared spectrometry, 1H nuclear magnetic resonance, elemental analysis and gas chromatograph-mass spectrometry. The ligand synthetic route was optimized. The fluorescence properties of the complex in solid state, in different kind of solvents and in solutions with different pH values were investigated in detail. The results show that the yields of DSPDA and 4-SPDA reach over 78% by Wittig-Horner reaction and other eight pyridine-2, 6-dicarboxylic acid derivatives with different substituents on pyridine ring, and their complexes with Tb(Ⅲ) are also obtained. The fluorescence intensities of the complexes with electron-donating groups are more intense than those of the complexes with electron-withdrawing groups on pyridine ring; fluorescence intensities of the complexes are the strongest in neutral solution (pH=7), and the less the dipole moment of solvent molecule is, the stronger the fluorescence intensity is. It is found that the two ligands (4-APDA and DSPDA) are the good sensitizers for Tb(Ⅲ) ion.
A novel compound 4,8,10-trimethyl-2-(3,5-dimethylpyrazol)-pyrido-[2',3':3,4]-py-razol-[1,5-5-a]-pyrimidine(C17H18N6) has been synthesized from 2,6-dichloro-4-methylnico-tino-nitrile,hydrazine and acetylacetone by substitution and cyclolization.The structure was charac-terized by elemental analysis,1H NMR and IR,and single-crystal structure was determined by X-ray diffraction analysis.The compound crystallizes in the monoclinic system,space group P21/c with a = 8.0338(9),b = 28.618(3),c = 7.2688(8),β = 111.051(2)o,V = 1559.6(3) 3,Z = 4,Dc = 1.305 g/cm3,μ = 0.083 mm-1,Mr = 306.37,F(000) = 648,S = 0.971,the final R = 0.0795 and wR = 0.1746 for 1457 observed reflections(Ⅰ > 2σ(Ⅰ)).The results demonstrate that the pyridine,pyrazole and pyrimidine rings are nearly coplanar,which is evident from the dihedral angles among the four rings in the range of 0.13～4.15o.The face-to-face π-π stacking interactions among pyridine,pyrazol and pyrimidine rings result in a supramolecular crystal,in which they seem to be effective in stabilizing the structure.Meanwhile,the fluorescence properties of the title compound were discussed,which showed very strong fluorescence.The calculated results(selected bond lengths,bond angles and torsion angles) are all typical and agree well with the experimental results,which demonstrates that B3LYP/6-31+G* is suitable for the title compound.
