Design, synthesis and characterization of hierarchical porous stacked thin films based on MOFs and ordered mesoporous oxides

Abstract

Sub-micrometre thin alternate bilayers of materials with appropriate refractive index contrast are widely used for the assembly of sensors based on the stimuli-responsiveness of such 1D photonic crystals (PC). A new degree of complexity was recently enabled by the availability of highly ordered multiporous materials. Specifically, we studied the integration of two kinds of materials with different refractive indexes: Si- and Ti-based highly ordered mesoporous oxides with defined pore sizes, and both Zr- and Zn-based Metal Organic Frameworks (UiO-66 and ZIF-8 MOFs), featuring microporosity and chemically tunable affinity. Synthesis conditions must guarantee the preservation of structural and chemical integrity when both building blocks are assembled into bilayers. Thus, we studied the influence of usually employed synthetic procedures for the selected individual materials on the available porosity, crystalline structure, and morphology of the obtained bilayers, and propose suitable paths for the integration of multilayers capable of acting as 1D-PCs with both meso- and microporosity.