Syntheses, structures, photoluminescence, and magnetic properties of (3,6)- and 4-connected lanthanide metal–organic frameworks with a semirigid tricarboxylate ligand

Abstract

Lanthanide coordination polymers [LnL(DMF)₂]·0.25H₂O [Ln = La (1), Ce (2), Pr (3), Nd (4), Sm (5), Eu (6), Gd (7), Tb (8), Dy (9), Ho (10), Er (11), and Tm (12)], and [GdL(H₂O)₃] (7′) (H₃L = 5-(4-carboxy-2-nitrophenoxy)-isophthalic acid), have been synthesized under hydro- and solvothermal conditions, respectively. Compounds 1–12 exhibit the same three-dimensional (3D) architecture, which is built up from binuclear paddle-wheel building blocks, and their resulting frameworks can be rationalized as rarely reported flu-3,6-C2/c topology. Compound 7′ crystallizes in the monoclinic system, space group P2₁/c. The ligands (L) bridge the Gd(III) centers to form 3D frameworks featuring a zeolite BCT topology, which have been unreported based on rare earth metals until now. Moreover, compound 6 exhibits characteristic red luminescent properties of Eu(III) complexes. The magnetic susceptibilities, over a temperature range of 2.0–300 K, of 7 and 7′ have also been investigated.