Syntheses And Luminescence Of Europium And Terbium Complexes With 2,6-bis(p-substituted Benzoylactyl)Pyridine

A series of bis((?)-diketones) were synthesized through the reactions between Dimethyl 2,6-Pyridinedicarboxylate and corresponding ketones under NaH. These bis((?)-diketones) are as follows: 2,6-bis[3-phenyl-3-oxopropanoyl] pyridine (L1), 2,6-bis[3-(4-methylphenyl) -3-oxopropanoyl] pyridine (L2), 2,6-bis[3- (4-methoxylphenyl)-3-oxopropanoyl] pyridine (L3), 2,6-bis[3-(4-chlorophenyl)-3-oxopropanoyl] pyridine (L4) and 2,6-bis[3-(4 -bromophenyl)-3-oxopropanoyl] pyridine (L5). All structures of the compounds were characterized by IR, UV, 1H-NMR spectra, MS and X-ray single crystal diffraction. The results showed that compounds displayed their enol isomers so that it's easy for H2L to coordinate with rare earth ions after reacting with NaOH and compounds L2, L4 and L5 are new compounds.Compounds L1-L5 being the first ligands, we synthesized the duality complexes with Eu(Ⅲ) and Tb(Ⅲ), and the ternary complexes with 1,10-phenanthroline as the second ligand. The complexes were characterized by IR, UV, thermo-gravimetric analysis, elementary analysis and fluorescence spectrum. The results show that all the free ligands can emit fluorescence, these Eu(Ⅲ) complexes emit strong red fluorescence, all the positions of fluorescence emission are about 615 nm, and the fluorescence intensity of the ternary complexes are much stronger than that of the duality complexes. These phenomenon were well explained by crystallized water, the second ligand, different groups of ligands L1-L5 and energy-matching mechanism.We also synthesized trinuclear complex of compounds L1-L5 with Eu(Ⅲ) and d-metal ions like copper ion, zinc ion, and magnesium ion and studied their fluorescence properties as the former papers most focus on studying magnetic character of the complexes and so few of them investigated the fluorescence of this kind of complexes.Crystal structure for new compound L2 was measured by X-ray diffractomer and the data were as follows: L2: C₂₅H₂₁NO₄, Crystal system Monoclinic, Space group C2/c, a = 19.2915(18) (?), b = 9.7207(11) (?), c = 11.1047(11) (?),α= 90 o,β= 100.831(4) o,γ= 90 o, V = 2045.3(4) (?)3, Z = 4, F = 840, Dcalc. = 1.297 g/cm-3,μ= 0.09 mm^-1, R₁ ( >2σ(I) ) =0.0439, wR2 ( >2σ(I) )= 0.145.