Crystalline Porous Materials Inspired by Metallodrugs

Abstract: Inspiration for developing robust porous materials from sustainable reagents was acquired by determining the crystal structures of bismuth subsalicylate and bibrocathol, two long-used and commonly available bismuth-based pharmaceuticals. From these insights, a number of coordination polymers and metal-organic frameworks (MOFs) were developed, facilitating the synthesis of robust porous materials from sustainably sourced reagents. The structural investigations were carried out using advanced transmission electron microscopy techniques, including three-dimensional electron diffraction.Using Bi3+ to synthesize MOFs, a previously unreported type of the so-called ‘breathing effect’ was observed in two materials. The breathing originates in the inorganic part of the obtained metal-organic structures and was thoroughly investigated for the bismuth-carboxylate framework SU-100. Taking further inspiration from bismuth-based metallodrugs, pseudo-polymorphs of the metallodrug bismuth subgallate were prepared, yielding coordination networks of varying periodicities. Following this line of work, a bismuth-phenolate MOF was prepared using ellagic acid—a phenolic molecule isolated from plant-based waste. The resulting material, SU-101, can be synthesized in water under ambient conditions and exhibits excellent chemical robustness, remaining crystalline upon exposure to harsh aqueous solutions and toxic gases. A second metal-ellagate framework, SU-102, was prepared using zirconium, yielding an equally robust framework. The material was evaluated for the capture and degradation of pharmaceutical pollutants from the effluent of a wastewater treatment plant, showing a selectivity towards cationic pharmaceuticals. This work highlights the potential of using natural products to create high-performing and chemically robust porous materials, for use in applications such as water remediation and the adsorption of toxic gases.