Highly efficient and selective detection of sulfur ions and picric acid through salamo-Cd(II) coordination polymer chemosensor

Abstract

A salamo-Cd(II) coordination polymer [Cd(HL)2(4,4ʹ-bipy)]n (CP-Cd(II)) was synthesized by introducing a auxiliary ligand 4,4ʹ-bipy to the host ligand H2L (4-chloro-4ʹ-bromo-6-bromo-6ʹ-tert-butyl-2,2ʹ-[ethylenedioxybis(nitrilomethylidyne)]di-phenol), and used as a fluorescent chemical sensor to detect sulfur ions (S2−) and picric acid (PA). Single crystal X-ray analysis demonstrated that the Cd(II) atom has a slightly distorted hexa-coordinate octahedron configuration and forms an infinite one-dimensional chain structure due to the intervention strategy of the auxiliary ligand. In fluorescence method, the sensor CP-Cd(II) exhibits good selectivity and sensitivity for S2− and PA with fluorescence turn-on and off effects sequentially. Additionally, the quenching efficiency of PA remains unchanged even after the sensor has been used for four cycles. At the same time, the sensor CP-Cd(II) can quickly detect S2− and PA within 10 s, which make them charming, recoverable and reliable luminescent coordination polymer sensor materials for detecting S2− and PA. The sensing mechanisms were attentively explored by mass spectrometry analysis, spectroscopic studies and density functional theory (DFT) calculations. Furthermore, the potential application of the sensor for further detection of S2− ions and PA in environmental systems was studied through actual water sample detection.