(428a) Nanometer-Thick Metal-Organic Framework Films for Rapid Permselective Gas Mixture Separation

Metal-organic frameworks (MOFs) are hybrid inorganic/organic compound made by coordination of organic linkers with metal nodes, leading to a crystalline framework with a permanent microporosity. The flexibility in the selection of metal and organic building blocks, a relatively rapid crystallization kinetics, and possibility to synthesize frameworks with Å-scale pore aperture has led to rapid adoption of MOFs in molecular separation. Thin MOF films have been pursued intensively motivated by the desire to prepare membranes for selective gas separation.[4-6] To achieve membranes with high throughput, as in Å-scale biological channels with nanometer-scale pathlengths, MOF films with the minimum possible thickness, down to just one unit cell, are highly desired. However, the state-of-the-art methods yield MOF films with thicknesses exceeding 40 nanometers.

In this presentation, I will discuss a deposition method from ultra-dilute precursor mixtures that within minutes yields uniform unit-cell-thick MOF films on crystalline substrates with crystallographic registry with MOF. For example, two-dimensional (2D) crystalline zeolitic imidazolate frameworks (ZIF) and UiO-66 films with thickness of a unit-cell could be achieved, enabling rapid permselective molecular transport, in particular record-high separation performance for H2/N2 and H2/CO2 gas mixtures. The method reported here will likely accelerate the development of 2D crystalline and ultrathin amorphous MOF films for applications ranging from separation membranes to sensors and patterning for microelectronic applications.