Six Ln (III) Coordination Polymers with a Semirigid Tetracarboxylic Acid Ligand: Bifunctional Luminescence Sensing, NIR-Luminescent Emission, and Magnetic Properties

Two series of lanthanide metal organic frameworks (Ln–MOFs) [Ln(HL)(H2O)3]·H2O and [Ln(HL)(H2O)2] (Ln = Tb, 1; Er, 4; Tm, 5; Yb, 6; and Dy, 2; Ho, 3) have been successfully assembled by Ln3+ ions and asymmetric polycarboxylate ligand 3-(3′,5′-dicarboxyl-phenoxy) phthalic acid (H4L). The crystal structures, photoluminescence, and magnetic properties of these compounds have been investigated. Complexes 1, 4, 5, and 6 are isostructural and show 2D layer frameworks constructed by hydrogen bonding interactions between the coordination water molecules and the O atoms of the carboxyl group. Complexes 2 and 3 show 3D frameworks with two different interlayer channels decorated by ligands and lanthanide metals. The emission spectra show that complex 1 displays an intense green light emission and can selectively and sensitively detect for Fe3+ ion and nitromethane. In addition, near infrared (NIR) luminescence and magnetic susceptibility measurments further show that these compounds are promising functional materials.