A two-dimensional cadmium-based metal–organic framework as an excellent probe: highly selective luminescent “turn on” detection of tetrahydrofuran and quantitative analysis of water

Abstract

The sensing of organic solvents and the determination of their water content are necessary conditions for ensuring environmental safety and organic solvent use. Herein, we selected a water-stable Cd-MOF, possessing 2D layers and amine groups, and optimized the synthesis conditions. The intensity of emission peaks gradually weakens with the increase in excitation wavelength in the range of 290–350 nm. The luminescent emission peaks exhibits a significant red shift with an increase in excitation wavelength at 355–400 nm. Tetrahydrofuran (THF) can significantly enhance the luminescent intensity of Cd-MOF compared to the others. Even in the presence of 5% volume fraction of other solvents, THF still shows a strong enhancement effect. These results confirm that this Cd-MOF can quickly and selectively detect THF through luminescent “turn on”. Furthermore, the emission intensity of the Cd-MOF in THF gradually recedes with the increase in water, indicating its potential for the determination of water content of THF. The corresponding limit of detection is 0.14%, lower than that of some reported compounds. The interaction of THF and the amine groups of the ligand may lead to this specific enhancement of luminescence. In addition, the mixed matrix membrane with the functionality of MOF materials and the processability of polymers was synthesized, which can detect Fe³⁺, CrO₄²⁻, and Cr₂O₇²⁻ in water.