Synthesis, crystal structure and properties of novel isostructural two-dimensional lanthanide-based coordination polymers with 2,3,5,6-tetrafluoro-1,4-benzenedicarboxylic acid

Five new isostructural two-dimensional lanthanide-based coordination polymers with the formula Ln2(F4BDC)3(DEF)2(EtOH)2-2(DEF) (Ln = Tb, 1; Gd, 2; Eu, 3; La, 4; Nd, 5; F4BDC2− = 2,3,5,6-tetrafluoro-1,4-benzenedicarboxylate ligands; DEF = N,N′-diethylformamide), have been synthesized by reaction of Ln(NO3)3 and F4BDC in a DEF/EtOH solvent mixture. The compounds were characterized by single-crystal and powder X-ray diffraction. In all cases, the metal ion is coordinated by nine oxygen atoms from two bidentate μ2-F4BDC2− ligands, two bridging μ2-F4BDC2− ligands, one μ3-F4BDC2− ligand, one DEF molecule and one EtOH molecule forming a tri-capped trigonal prism. The Ln(1) metal ion is linked to an adjacent Ln(1) metal ion through the oxygen atoms of two bridging μ2-F4BDC2− ligands and two μ3-F4BDC2− bridging ligands to form a Ln2O18 dimer. The Ln2O18 polyhedra building units are linked to each other through four F4BDC2− ligands to form 2D sheets that are held together by hydrogen bonding to form a 3D framework. Compounds 1–5 were further characterized using thermogravimetric analysis and infrared spectroscopy. Studies of the photoluminescence properties of compounds 1 and 3, as well as the catalytic activity of compounds 3–5 in the Biginelli reaction, are presented.