Two-dimensional layered MOF nanosheets with multiple binding sites for selective detection and removal of Fe(III) ions

Ultrathin MOF nanosheets with multiple binding sites on the surface were rationally designed and assembled, which showed great detection and removal ability of Fe3+. [Display omitted] •A novel MOF nanosheet with multiple binding sites on the surface was rationally designed and assembled, which showed great detection and adsorption ability for Fe3+.•The study represents the first example of MOF nanosheets for simultaneously sensing and removing heavy metal ions.•Possible mechanisms of Fe3+ detection and removal were investigated in detail.•This work provides a guideline for the design and synthesis of MOF nanosheet materials with both detection and removal functions. Heavy metal contamination has become an urgent global concern, posing a significant threat to our environment and health. Hence, it is critical to exploit functional materials for heavy metal ions sensing and elimination. However, the development of multifunctional materials that can simultaneously accomplish the selective detection and removal of the metal ions remains a significant challenge. In this work, a two-dimensional (2D) layered metal–organic framework (LMOF) functionalized with diverse binding sites has been utilized to concurrently detect and remove Fe3+ ions. The LMOF [Zn(hsb-2) (5-aipa)](HSB-W15) was rationally designed and constructed from the mixed ligands of hsb-2 (1,2-bis(4′-pyridylmethylamino)-ethane) and 5-aipa (5-aminoisophthate) under mild condition. In addition, the corresponding ultrathin nanosheets HSB-W15-NS were also obtained by adapting the instant in situ exfoliation (IISEM) method. Owing to the ultrathin nanosheet morphology and an abundance of active sites on the surface, HSB-W15-NS nanosheets can function as an effective fluorescent sensor to detect Fe3+ and Cr3+ ions. Exceptionally, HSB-W15-NS can also be used to selectively capture Fe3+ ions from water, with up to 93 % removal efficiency, and the adsorption equilibrium attained in 5 min. The sensing and adsorption processes were investigated based on kinetic model analysis, Fourier transform infrared spectroscopy, Raman spectrum analysis, density functional theory calculations, and control experiments. This work inspired the development of ultrathin 2D MOF nanosheets for applications in environmental protection.