Probe anchored porous organic polymer monolithic architectures as optical sensor for ultra-trace analysis of Hg2+ in water samples

Abstract

In this article, we have demonstrated an effective strategy to detect and remove the toxic Hg2+ by an ion-selective optical sensor using chromoionophoric receptor that is homogenously dispersed onto the surface of porous organic polymer (POP) template. Herein, we present a detailed summation of the synthesis of different POPs by employing various kinds of monomers and crosslinkers to discover excellent structural property materials that could cater to the needs of an optical sensor. The resultant POP from the bulk polymerization of N,N-dimethyl allylamine (DMA), and trimethylolpropane triacrylate (TMPTA), i.e., poly(DMA-co-TMPTA), manifested a higher surface area with pore size, thus has been utilized as the substrate material for the fabrication of the sensor. Further, the chromoionophoric coordinating ligand, i.e., 7-4(diethylamino)phenyldiazenyl quinolin-8-ol (DPDQ), is immobilized as receptor molecules onto the POP template for ultra-trace detection of Hg2+. The surface dispersed receptor forms stable 1:1 charge-transfer complexes [Hg2+-DPDQ] with a striking naked-eye color transition from pale orange to bright reddish-brown. The developed optical sensor offers an ultra-fast, selective response for Hg2+ with a lower detection limit of 0.1 μg/L (ppb) in the linear range of 0–100 μg/L. The regeneration of the sensor is envisaged with 0.02 M HCl and can be reused for up to six sensing cycles. Actual water samples from different geographical locations of India are tested using the developed sensor, and the method proved effective for real-time monitoring of Hg2+.