Abstract
Five crystal complexes {[Eu2(TPTZ)2(mNBA)6(H2O)2]·2CH3OH}n (1), [Eu(TPTZ)(CF3COO)(H2O)5]·Cl2·CH3CH2OH (2), {[Yb2(TPTZ)2(BDC)3]·2H2O}n (3), [Yb(TPTZ)Cl(H2O)4]·Cl2 (4) and [Er(TPTZ)(TTA)Cl2] (5) (mNBA = m-nitro benzoate, BDC = terephthalate, TTA = thenoyltrifluoroacetone, TPTZ = 2,4,6-tri(2-pyridyl)-1,3,5-triazine) have been synthesized. The single X-ray diffraction reveals that TPTZ is mainly in the trident coordination mode and organic aromatic carboxylic acids are in the multiple coordination modes in the crystals. The composition of solvents, reaction temperature and reactant ratios all affect the composition and structure of the formed crystals. Crystals 1 and 3 belong to triclinic system, while the other three belong to monoclinic system. Among them, Crystal complexes 1 and 3 are coordination polymers. The other three crystals are mononuclear complexes with LnШ ions in the asymmetric environment. Both of the Crystal complexes 1 and 2 show strong luminescence emissions of Eu3+. The luminescence lifetimes of the two complexes are 0.761 ms and 0.447 ms, respectively. In addition, their luminescence quantum efficiencies are 25.0% and 16.7%, respectively.
Highlights
The lanthanide complexes have a great deal of applications in the fields such as single-molecule magnets, biomedicine, electro-luminescence devices, laser-systems and optical communications [1,2,3,4,5].f-f electron transitions of lanthanide ions are forbidden by the parity rule
Ligand, the band at 1370 cm−1 was attributed to the breathing vibration of the center ring and the band at 993 cm−1 was attributed to the bending vibration of the pyridyl ring
1383–1382 and 1012–1008 cm−1 in the Crystal complexes 1–5, respectively, indicating that nitrogen atoms of the center ring and the pyridyl ring were coordinated with the metal ions [15,16]
Summary
The lanthanide complexes have a great deal of applications in the fields such as single-molecule magnets, biomedicine, electro-luminescence devices, laser-systems and optical communications [1,2,3,4,5]. Some neutral or anionic organic ligands, such as aromatic carboxylic acid, have been introduced. These organic ligands have excellent light absorption abilities and can transfer energy to lanthanide ions due to so-called “antenna effect” [7,8]. M-nitrobenzoic acid (mNBA) and thenoyltrifluoroacetone (TTA) ligands are typical organic ligands, which can form stable complexes with lanthanide ions [27,28,29]. Five crystal complexes with distinct composition and structure have been synthesized with central ions of Eu, Yb and Er. In addition, the luminescence properties of the europium complexes have been discussed
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