A series of three dimensional lanthanoid(III)-metal-organic frameworks with zwitterionic linker

Abstract

A series of isostructural 3D lanthanoid coordination polymers, {[Ln(µ4-cbpy)2]Br·xsolvent}n (Ln = La(1), Pr(2), Nd(3), Sm(4), Gd(5), Tb(6), Dy(7) and Ho(8), (H2cbpy)Br = 4-carboxy-1-(4-carboxybenzyl)pyridinium bromide), have been solvothermally synthesized and characterized by single-crystal X-ray diffraction, IR and elemental analysis. Powder X-ray diffraction (PXRD) and thermal analyses (TG, DTA and DTA) of 1–8 were also investigated. The single crystal X-ray diffraction analyses revealed that 1–8 were isostructural and crystallized in the monoclinic space group C2/c. In the complexes, each cbpy– acts as a tetrakis(monodentate) to connect to four Ln(III) ions. A pair of Ln(III) ions are coordinated by four carboxylate oxygen atoms to form paddle-wheel {Ln2(RCOO)4} secondary building units which are connected by four cbpy– ligand to form a 3D structure with scu topology.