Syntheses, strucutres, and luminescence properties of a new family of three-dimensional open-framework lanthanide coordination polymers

摘要

Deprotonation of 2,6-naphthalenedicarboxylic acid (H_2NDC) with pyridine followed by its copolymerization with Ln(III) nitrates (where Ln = Eu, Tb, Ce) in DMF at room temperature gave a family of 3-D open-framework lanthanide coordination polymers, formulated as {[Ln_2(NDC)_3(DMF)_4]·mH_2O}n (where Ln = Eu, Tb, Ce, 1-3; M = 3,4, 2 for 1-3, respectively, DMF = N,N'-dimethoxylformamide, and H_2NDC = 2,6-naphthalenedicarboxylic acid) on the basic of elemental analysis and single-crystal X-ray diffraction. Compounds 1-3 were isostructural and crystallized in triclinic space group (P(-1). In these structures, lanthanide ion dimers were interlinked together by NDC ligands with three different carboxylate coordination modes, to yield scaffolds with 3-D interconnecting tunnels where enclathrated water molecules residue. The results of IR and TG were consistent with the structural determinatino results. Fluorescence measurements show tht 1 and 2 emit strong red and gree light, respectively, upon irradiation with UV-vis light source. However, these open framework collapsed upon desolvation as evidenced by XRPD investigations,which renders their potential use as fluorescent sensors impossible.