Syntheses, Structures, and Photoluminescence of One-Dimensional Lanthanide Coordination Polymers with 2,4,6-Pyridinetricarboxylic Acid

Nine one-dimensional (1D) lanthanide(III) coordination polymers with the formulas {[La(pta)(H 2 O) 4 ]·2H 2 O} n ( 1 ), {[Ln(pta)(H 2 O) 5 ]·4H 2 O} n [Ln = Sm ( 2 ), Eu ( 3 ), Tb ( 4 ), Ho ( 5 )], and {[Ln(pta)(H 2 O) 3 ]·4H 2 O} n [Ln = Dy ( 6 ), Er ( 7 ), Tm ( 8 ), Yb ( 9 )] (H 3 pta = 2,4,6-pyridinetricarboxylic acid) have been synthesized by reacting the corresponding rare earth salts with H 3 pta at room temperature. The X-ray structure analyses show three kinds of 1D chain structures. Complexes 2 − 5 and 6 − 9 are isostructural, respectively. Complex 1 crystallized in the triclinic with P 1 space group, 2 − 5 crystallized in the orthorhombic with P na2 1 space group and 6 − 9 crystallized in the monoclinic with P 2 1 / c space group. In the three kinds of structures, H 3 pta displays two different coordination modes, and there are intramolecular π−π stacking interactions between the pyridyl ring planes. The complexes of Sm(III), Eu(III), Tb(III), and Dy(III) exhibit the corresponding characteristic luminescence in the visible region at an excitation of 305 nm, and the complexes of Er(III) and Yb(III) show luminescence in the near-infrared region upon excitation of UV rays.