Composite Eu@IMU-Cd as a Fluorescence Sensor for the Detection of Methylparaben in Real Liquor Samples

Abstract

A one-dimensional chain coordination polymer, {Cd₄(bdppy)₂(H₂O)₆}_n (IMU-Cd), was initially synthesized via a solvothermal reaction using the ligand 2,6-bis(3,4-dicarboxyphenoxy)pyridine (H₄bdppy). Subsequently, Eu³⁺ ions were incorporated into IMU-Cd via a one-pot synthesis to yield its postmodified composite material, Eu@IMU-Cd. The experimental investigations showed that Eu@IMU-Cd remained stable in different solvents as well as over a wide pH range. It was found that Eu@IMU-Cd was able to emit the characteristic peaks of Eu³⁺ ion and produced a fluorescence quenching effect in the presence of methylparaben (MP) and thus could be used as a fluorescent probe for the detection of MP. Moreover, its identification of MP by Eu@IMU-Cd exhibited high selectivity, reusability, and anti-interference, and the limit of detection of MP was found to be 25.6 nM. A combination of experiments and theoretical calculations was used to elucidate the detailed fluorescence mechanism for the identification of MP by Eu@IMU-Cd. Moreover, the films based on Eu@IMU-Cd were fabricated to achieve visual detection in the presence of MP. It is worth emphasizing that the experiments of determining MP in real liquor samples displayed that the spiked recovery was located in the range of 88.64%–97.86% with the RSD of less than 1.82%, which indicated that Eu@IMU-Cd had an outstanding capability for the exploration of MP in actual samples.