Alkali-Metal-Templated Assemblies of New 3D Lead(II) Tetrachloroterephthalate Coordination Frameworks

Abstract

A series of novel metal–organic frameworks (MOFs) have been assembled from PbII and 2,3,5,6-tetrachloro-1,4-benzenedicarboxylic acid (H2BDC-Cl4) by simply adding different alkali metal ions as templates. When only lead nitrate is used, a robust 3D open framework [Pb(BDC-Cl4)(MeOH)2]n (1) with pts topology can be obtained. Incorporating the lighter LiI or NaI ions into the above PbII/BDC-Cl4 system results in two unique isostructural 3D PbII–LiI and PbII–NaI heterometallic frameworks, {[PbLi2(BDC-Cl4)(μ2-OH)2](H2O)}n (2) and [PbNa2(BDC-Cl4)(μ2-OH)2]n (3), which are built from the combination of a 3D rod-packing PbII-carboxylate framework and a 3D NaI–BDC-Cl4 (or LiI–BDC-Cl4) network. When the heavier KI ion is applied, the similar reaction affords a 3D MOF [Pb2(BDC-Cl4)2(DMF)3]n (4), which represents the first pillar-layered PbII coordination network with a (3,5)-connected gra topology. The results illustrate the powerful effect of the alkali-metal templates in MOFs assemblies. The solid-state properties such as thermal stability and luminescence of 1–4 have also been studied.