Synthesis, crystal structure and fluorescence properties of terbium complexes with phenoxyacetic acid and 2,4,6-tris-(2-pyridyl)-s-triazine

Two complexes of Tb3+, Gd3+/Tb3+ and one heteronuclear crystal Gd3+/Tb3+ with phenoxyacetic acid (HPOA) and 2,4,6-tris-(2-pyridyl)-s-triazine (TPTZ) have been synthesized. Elemental analysis, rare earth coordination titration, inductively coupled plasma atomic emission spectrometry (ICP-AES) and thermogravimetric analysis-differential scanning calorimetry (TG-DSC) analysis show that the two complexes are Tb-2(POA)(6)(TPTZ)(2)center dot 6H(2)O and TbGd(POA)(6)(TPTZ) (2)center dot 6H(2)O, respectively. The crystal structure of TbGd(POA)(6)(TPTZ)(2)center dot 2CH(3)OH was determined using single-crystal X-ray diffraction. The monocrystal belongs to the triclinic system with the P-1 space group. In particular, each metal ion is coordinately bonded to three nitrogen atoms of one TPTZ and seven oxygen atoms of three phenoxyacetic ions. Furthermore, there exist two coordinate forms between C6H5OCH2COO- and the metal ions in the crystal. One is a chelating bidentate, the other is chelating and bridge coordinating. Fluorescence determination shows that the two complexes possess strong fluorescence emissions. Furthermore, the fluorescence intensity of the Gd3+/Tb3+ complex is much stronger than that of the undoped complex, which may result from a decrease in the concentration quench of Tb3+ ions, and intramolecular energy transfer from the ligands coordinated with Gd-3+ ions to Tb3+ ions. Copyright (C) 2015 John Wiley & Sons, Ltd.