Hydrothermal synthesis and crystal structure of two new lanthanide coordination polymers with 1,2-phenylenediacetate

Two new compounds {[Ln2(1,2-pda)3(H2O)2]· 2H2O} n (1,2-H2pda = 1,2-phenylenediacetic acid, Ln = Tb, 1; Ho, 2) were prepared by hydrothermal reaction and characterized by X-ray crystallography. The Ln3+ is nine-coordinate by eight oxygen atoms of six 1,2-pda ligands and one oxygen of water. Ln3+ ions are bridged by 1,2-pda ligands via bridging/chelating-bridging pentadentate and chelating-bridging/chelating-bridging hexadentate coordination to form 3-D framework structures. Complex 1 emits strong green fluorescence corresponding to 5D4 ⟹ 7Fj (j = 6–3) transitions of the Tb3+.