A Turn-Off Fluorescent Sensor (Dy1-xCex-BTC) for Detection of Acetaldehyde with High Sensitivity and Selectivity

A series of dual-lanthanide metal–organic frameworks (MOFs: Dy 1-x Ce x -BTC) have been successfully prepared by hydrothermal method using dysprosium (Dy 3+ ) and cerium (Ce 3+ ) ions as metal sources and 1,3,5-benzenetricarboxylic acid (H 3 BTC) as organic ligand, confirmed by XRD patterns and FT-IR spectra, and then the luminescence property, the application in detecting small organic molecules and structural stability have been discussed. Among the samples, Dy 0.8 Ce 0.2 -BTC exhibited two strongest emission peaks located at 485 nm and 578 nm under the excitation at 295 nm, which are attributed to the excited electronic transitions of Dy 3+ from 4 F 9/2 to 6 H 15/2 and 6 H 13/2 . However, Dy 0.8 Ce 0.2 -BTC immersed in the solution of acetaldehyde (AH) demonstrated an obvious luminescence quenching with the calculated quenching constant ( K sv ) and the limit of detection ( LOD ) as 7.08 × 10 3  M −1 , 5.36 × 10 –7  M and high selectivity among the other tested organic solvents. Meanwhile, it revealed that the MOF could maintain good microstructural and recycle stability in deionized water, indicating a great potential as a turn-off fluorescent sensor for AH detection. Besides, the luminescence quenching mechanism was deduced from competitive absorption.