Hybrid Membrane of Agarose and Lanthanide Coordination Polymer: a Selective and Sensitive Fe(3+) Sensor

A new hybrid membrane was prepared by a facile method based on a highly luminescent lanthanide coordination polymer and agarose. The soft membrane was characterized by FT-IR, PXRD, SEM and luminescence. It is found that the soft membrane is a highly selective and sensitive sensor, among 19 metal ion solutions of Fe(3+), Mg(2+), Li(+), Ca(2+), Zn(2+), Cu(2+), Ba(2+), Mn(2+), Ru(3+), Cr(3+), Ag(+), Sr(2+), Cd(2+), Na(+), Ni(2+), Pb(2+), Fe(2+), Hg(2+) and Ca(2+), only Fe(3+) quench the luminescence. The sensing results can be distinguished by the naked eye in daylight or by irradiation of a portable UV light at the scene. Mechanism studies reveal the sensing is due to the decomposition of the coordination polymer 1 which induced by slow permeation of Fe(3+). Further studies found anions of BO3(-), CO3(2-), H2PO4(-), Br(-), Cl(-), ClO4(-), H2PO4(-), I(-), IO3(-) and NO3(-) will not quench the luminescence of the hybrid membrane, which imply that other anions in water would not disturb the detection result.