Mixed matrix membranes containing fluorescent coordination polymers for detecting Cr2O72− with high sensitivity, stability and recyclability

Abstract

Three coordination polymers (CPs) were synthesized by using Cd^II, fluorescent 9,10-di(4-pyridyl)anthracene (dpa), and cyclohexane-1,4-dicarboxylic acid (H₂cda), and they are [Cd₂(dpa)₂(cda)Cl₂]_n (1), [Cd(dpa)₂(cda)]_n (2) and [Cd(dpa)(cda)(H₂O)]_n (3). Both 1 and 2 are fluorescent and contain nonporous layers. 3 is an isomer of 2 and contains a porous diamondoid network. Fluorescent mixed matrix membranes were prepared by dispersing the particles of 1 or 2 within the matrix of polymethyl methacrylate, and showed high sensitivity and selectivity for detecting Cr₂O₇²⁻ in water. Both stability and recyclability of the MMMs were remarkably higher than those of the CP powders.