Polymeric Zinc Ferrocenyl Sulfonate as a Molecular Aspirator for the Removal of Toxic Metal Ions

A porous bilayered open coordination polymer Zn(4,4'-bpy)(2)(FcphSO(3))(2)(n) (1; FcphSO(3)Na=m-ferrocenyl benzenesulfonate), has been assembled from Zn(NO(3))(2), m-ferrocenyl benzenesulfonate, and the bridging ligand 4,4'-bipyridine (4,4'-bpy). Ion-exchange induced products Cd(0.6)Zn(0.4)(4,4'-bpy)(2)(FcphSO(3))(2)(n) (2), Zn(0.75)Pb(0.25)(4,4'-bpy)(2)(FcphSO(3))(2)(n) (3), and Cu(0.5)Zn(0.5)(4,4'-bpy)(2)(FcphSO(3))(2)(n) (4) could be obtained directly by suspending a big single crystal of 1 into concentrated solutions of Cd(NO(3))(2), Pb(NO(3))(2), and Cu(NO(3))(2), respectively. Most importantly, the big single crystal of 1 could be partly regenerated after immersion into concentrated aqueous solutions of Zn(NO(3))(2). On the other hand, powdered 1 could also be used as a metal ion adsorbent because of the well-defined pore size and pore shape. Ion exchange takes place along with the process of ion sorption. The big single crystal of 1 removes harmful metal ions by means of ion exchange, whereas powdered 1 removes toxic metal ions mainly through ion sorption. Also, compound 1 could be employed as a multi-ion analysis fluorescent probe to detect dangerous metal ions, such as Pb(2+), Cd(2+), Ag(+), and Cu(2+). The compounds described in this study may have potential applications in the design of new molecular devices.