Structurally engineered probe infused porous polymer monolith as a solid-state visual sensing platform for Cd2+ ions.

This work describes an effective optical on-site sensor strategy for quantifying Cd²⁺ in aqueous samples using a tailor-made physically modified probe-immobilized porous polymer monolithic sensor. The bimodal macro/mesoporous polymer, namely poly(2-(trifluoromethyl) acrylic acid-co-trimethylolpropane triacrylate) (poly(TFMAA-co-TMPTA)) matrix, was fabricated by simple bulk polymerization, and was uniformly encapsulated with a chromophoric ligand, namely (E)− 5-(quinoline-8-yl-diazenyl)quinoline-8-ol (QDQ) by a direct impregnation process. The designed monolithic template and the concocted sensor were characterized using FE-SEM, EDAX, HR-TEM, SAED, XPS, N 2 adsorption isotherms, p-XRD, TGA and FT-IR. The optical sensor benefits from a uniformly interconnected mesostructured polymer template and showcased a superior sensing performance in selectively capturing the ultra-trace amounts of Cd²⁺. Furthermore, it displayed a dynamic optical property by enabling a distinct progressive visual color change from light orange to brick red due to the selective complexation of the QDQ probe with Cd²⁺. The solution pH, probe concentration, contact time, temperature, selectivity, and sensitivity were optimized to evaluate the best sensing performance, and the sensor showed a linear response range from 1.5–100 μg/L, with the lowest detection limit (LOD) of 0.53 μg/L. The theoretical calculations about the binding mechanism of QDQ probe molecules with Cd²⁺ were studied using density functional theory (DFT). The newly fabricated solid-state sensor affords a promising tool for detecting trace amounts of Cd²⁺ in real water and cigarette samples. [Display omitted] • Poly(TFMAA- co -TMPTA)QDQ is a Cd²⁺ selective solid-state opto-chemosensor. • The structural architecture of the polymer monolith enhances the sensor's selectivity and sensitivity. • The sensor renders a faster kinetic response by enabling easier diffusion of analytes to the binding sites. • A highly sensitive screening and quantification of Cd²⁺ with a detection limit of 0.53 μg/L is obtained. • Cd²⁺ binding with the QDQ probe is extensively studied using DFT calculations. [ABSTRACT FROM AUTHOR]