A phosphonate coordination polymer with highly sensitive detection of ascorbic acid and the proton conductivity of its polymer composites

Abstract

A phosphonate coordination polymer, [Cd(H3bmpa)2]n (1), based on Cd2+ ions and H4bmpa (H4bmpa = N-Benzyliminobis(methylenephosphonicacid)) was synthesized under hydrothermal conditions. It is characterized by single crystal X-ray diffraction, PXRD and TGA. Crystal structure indicates that adjacent Cd2+ ions are linked by oxygen atoms in the phosphonate groups to form a 1D chain structure. Adjacent 1D chains are further linked by hydrogen bonds to form a 2D planar structure. Complex 1 is a bifunctional material that has both fluorescent and proton conducting properties. It can detect ascorbic acid sensitively and selectively with a detection limit of 5 µM. To further improve the proton conductivity of Complex 1, PVA (Polyvinyl alcohol) was introduced with it to prepare the composites. The proton conductivity of 1@PVA-10 is 3.05 × 10−5S·cm−1 (323 K, 98% RH), which is two orders of magnitude higher than that of coordination polymer.