Fabrication of 5-R-isophthalic acid-modulated cadmium–organic coordination polymers and selectivity for the efficient detection of multiple analytes

Abstract

Excessive emission of inorganic ions and organic molecules can pose a potential threat to human health and the environment. Therefore, finding a way to detect contaminants is crucial. Coordination polymers (CPs) are of great practical importance as effective chemical sensors. Secondary auxiliary ligands with different functional groups were synthesized (by a hydrothermal method) and characterized: {[Cd₂(3-dpyp)(1,3-BDC)₂]·H₂O}_n (1), {[Cd(3-dpyp)_0.5(1,3-BDC)(H₂O)₂]·H₂O}_n (2), {[Cd₂(3-dpyp)(5-MIP)₂(H₂O)₃]·2H₂O}_n (3) and {[Cd(3-dpyp)(5-HIP)]·1.5H₂O}_n (4), where 3-dpyp = N,N′-di(3-pyridinecarboxamide)-1,3-propane, 1,3-H₂BDC = 1,3-benzenedicarboxylic acid, 5-H₂MIP = 5-methylisophthalic acid and 5-H₂HIP = 5-hydroxyisophthalic acid. Single-crystal X-ray diffraction (SCXRD) analysis showed that the four Cd-CPs exhibited fascinating two/three-dimensional structures. Moreover, Cd-CP-1–4 showed excellent stability in the pH range of 1–14 and in different organic solvents. Powder X-ray diffraction analysis and thermogravimetric analysis indicated that the Cd-CPs possessed high chemical and thermal stabilities. Furthermore, with the aim of “using waste to treat waste”, fluorescence properties showed that Cd-CP-1–4 could be used as multi-response sensors for Fe³⁺, MnO₄⁻ and nitrobenzene with high sensitivity, selectivity and efficiency.