Room temperature preparation method for thin MOF-5 films on metal and fused silica surfaces using the controlled SBU approach

As a representative of the IRMOF series, MOF-5 was deposited onto self-assembled monolayer modified metal and fused silica surfaces applying the controlled SBU approach (CSA) (SBU - secondary building unit). Although the controlled SBU approach was already used in some cases to deposit IRMOFs and other MOF (metal-organic framework) types on surfaces, this contribution is the first study concerned with basic processes of the deposition of IRMOFs onto SAM (self-assembled monolayers) coated substrates, like the carboxylate exchange between SBU precursor and SAM, the influence of different substrates, or the morphology differences resulting from different cyclic preparation procedures. The deposition of the first SBU layer (basic zinc perfluoromethylbenzoate) onto the surface and the carboxylate exchange during CSA was demonstrated by infrared reflection-absorption spectroscopy. The various aspects of the MOF deposition, such as the crystalline growth, the element distribution, the porosity, and the morphology of the thin films were addressed by powder X-ray diffraction (PXRD), energy-dispersive X-ray spectroscopy (EDX), nitrogen cryo-adsorption measurement, and scanning electron microscopy (SEM).