Two Lanthanide Metal-Organic Frameworks Based on Semi-Rigid T-Shaped Tricarboxylate Ligand: Syntheses, Structures, and Properties

By using a semi-rigid tripodal ligand 5-(4-carboxybenzyloxy)isophthalic acid (H3L) and lanthanide metal ions (Nd3+, Tb3+), two novel lanthanide metal-organic frameworks, namely, {[Nd2L2(DMF)4] DMF}(n) (1), and {TbL(DMF)(H2O)}(n) (2), were synthesized under mild solvothermal conditions and structurally characterized by X-ray single crystal diffraction. Compounds 1 and 2 are isostructural, in which L3- ligands linked dinuclear lanthanide metal-carboxylate units to form non-interpenetrated 3D network with (3,6)-connected topology. Luminescent investigations reveal that compound 1 displays the near-infrared emission at room temperature, and compound 2 can be employed as selective probe for Cr2O72- anion in aqueous solution based on luminescence quenching. Moreover, compound 2 exhibits catalytic activity for cyclo-addition of CO2 and epoxides under relatively mild conditions.