Tuning metal-organic frameworks to tailor structure and optimize gas absorption | Poster Board #540

Metal-organic frameworks (MOFs) are crystalline nano-porous high surface area supramolecular materials with highly tunable compositions and structures as a variety of organic ligands and metal nodes can be selected. These materials are utilized in applications such as drug delivery, catalysis, electronics, water purification, and gas sequestration. Typically MOFs are synthesized as powders composed of micron-scale crystals. MOFs can also be anchored to a surface via a self-assembled monolayer (SAM) to form a surface-anchored MOF (surMOF), typically deposited by alternating layer-by-layer solution-phase exposure of organic and inorganic precursors. The terminal functional group of the anchoring SAM can direct surMOF growth, which controls the surface morphology. This morphological control permits surMOFs to be tailored for different applications with smooth films desirable as dielectric layers for electronic devices and rougher films advantageous for gas applications. The Anderson Lab has recently been investigating Cu-BDC, a MOF composed of copper metal nodes and benzene-1,4-dicarboxylic acid (BDC) organic linkers, which is a potential sorbent for aromatic volatile-organic compounds (VOCs). VOCs are low molecular weight species that are highly volatile and have low water solubility, which are typically found in air pollution as byproducts from industrial applications. The Anderson lab explores variables to tune surMOF film growth and morphology with characterization undertaken using ellipsometry, atomic force microscopy, infrared spectroscopy, and x-ray diffractometry. Recent focus has compared solution-phase immersion deposition to spray coating the precursor components on carboxyl- and hydroxyl-terminated alkanethiol SAMs on gold. Different nanocrystallite structures were found to form depending on the deposition conditions. Current research is investigating Cu-BDC surMOFs and powders for gas capture and sensing of VOCs. Exposure experiments with VOCs, such as toluene and benzaldehyde, are characterized via infrared spectroscopy, x-ray diffractometry, scanning electron microscopy, and thermal gravimetric analysis. The capture of VOCs is being optimized for the CuBDC system and potential alternative MOF systems will be explored as well.