An anionic Cd-based coordination polymer exhibiting ion-exchange behavior for photoluminescence and selective dye adsorption

A 2D anionic Cd-based coordination host was constructed from the linkage of the metal ions and 6-sulfonicotinic acid (SNA, in situ generated from the breaking of disulfide bond in 6,6'-dithiodinicotinic acid) whose interior spaces are occupied with cationic [(CH3)(2)NH2](+) guests. The compound exhibits an interesting ion-exchange behavior for both encapsulation of lanthanide (Ln) ions and organic dye. Through the fixation of Ln(3+) within the host, the designed composite can be endowed with high photoluminescence property. Moreover, the free cations could be readily substituted by methylene blue (MB), with more than 90% of MB (10(-5) M) being selectively absorbed after 12 h, making the title compound to be a great medium for dye adsorption and separation.