An unusual porous metal-organic framework that demonstrates the highly efficient exchange of metal ions and the reversible adsorption of iodine.

An exceedingly rare porous metal-organic framework that is based on cadmium ions and multi carboxylate ligands, namely, Na(0.25)[(CH3)2NH2](1.75)[Cd(L)2]·x solvent (1, H2L=2-hydroxymethyl-4,6-bi(2'-methoxyl-4'-(2''-1''-carboxyl)-ethlene)-1,3,5-mesitylene), has been successfully synthesized under solvothermal conditions. Compound 1 exhibits a 2D network that is constructed from left- and right-handed helical chains. Furthermore, neighboring 2D layers are stacked to give a porous motif. Strikingly, compound 1 exhibits the highly efficient exchange of metal ions from the main framework components whilst maintaining the structural integrity and the crystallinity of the network. In addition, Compound 1 also shows outstanding performance in the reversible adsorption of iodine.