3D metal–organic frameworks polymers of Pr(III) and Eu(III) with pyridine-2,6-dicarboxylic acid: Synthesis, structure and luminescent properties

Pyridine-2,6-dicarboxylic acid (H2PDA) was used for the synthesis of two MOFs polymers {[Ln2(PDA)3(H2O)3]·H2O}n (Ln = Pr(1) and Eu(2)) with Pr(NO3)3·6H2O and Eu(NO3)3·6H2O under hydrothermal conditions and characterized by elemental analyses, IR spectroscopy, thermal analyses and single crystal X-ray diffraction. Both compounds crystallize in monoclinic system, space group P 21/c. Both of the two compounds are isomorphous and isostructural. Different rings exist in the title compounds and form the 2D metal–organic framework. The 3D structures are constructed through covalent bonds and hydrogen bonds. The thermal decompositions have been predicted with the help of thermal analyses (TG and DTG). Furthermore, the luminescent properties of 2 were studied in the solution of DMF at room temperature.

► Two MOFs polymers {[Ln2(PDA)3(H2O)3]·H2O}n (Ln = Pr(1) and Eu(2)) were synthesized and characterized. ► Both the 3D frameworks are assembled from the structure units containing three types of rings via hydrogen bond and OCO bridges. ► The thermal decompositions of 1 have been predicted with the help of thermal analyses and emission spectra of 2 have been identified.