Porous Two-Dimensional Monolayer Metal–Organic Framework Material and Its Use for the Size-Selective Separation of Nanoparticles

Rational bottom-up construction of two-dimensional (2D) covalent or noncovalent organic materials with precise structural control at the atomic or molecular level remains a challenge. The design and synthesis of metal-organic frameworks (MOFs) based on new building blocks is of great significance in achieving new types of 2D monolayer MOF films. Here, we demonstrate that a complexation between copper(II) ions and tri(β-diketone) ligands yields a novel 2D MOF structure, either in the form of a powder or as a monolayer film. It has been characterized by Fourier transform infrared, Raman, ultraviolet-visible, X-ray photoelectron, and electron paramagnetic resonance spectroscopies. Selected area electron diffraction and powder X-ray diffraction results show that the MOF is crystalline and has a hexagonal structure. A MOF-based membrane has been prepared by vacuum filtration of an aqueous dispersion of the MOF powder onto a porous Anodisc filter having pore size 0.02 μm. The porous MOF membrane filters gold nanoparticles with a cutoff of ∼2.4 nm.