Ionic Liquid-Assisted Exfoliation of Two-Dimensional Metal–Organic Frameworks for Luminescent Sensing

The exfoliation of two-dimensional metal–organic frameworks (2D MOFs) to prepare few-layered MOF nanosheets (MONs) has been of great interest in recent years. In this work, an efficient and environmentally friendly liquid-exfoliation method is developed to produce stable and high-concentration dispersions of few-layered Zn2(bim)4 MONs. Bulk Zn2(bim)4 can be successfully delaminated in ionic liquid and water mixed solvents, where the ionic liquid acts both as solvent and surfactant. The highest exfoliation rate is up to 47% with a [Omim]Cl volume ratio of 50%. In addition, the prepared Zn2(bim)4 MONs can be easily dispersed in an aqueous solution and stabilized for more than 2 weeks. Zn2(bim)4 MONs are used as a fluorescent sensor to detect metal ions in water and exhibit enhanced sensing ability for Fe3+ than bulk MOFs. The highly dispersive nature after delamination and easily accessible active sites on Zn2(bim)4 MON surface are all in favor of its high-performance in sensing.