Guest-directed synthesis reveals vast family of robust polyphenolic metal-organic frameworks

Structure directing agents (SDAs) are widely used in the synthesis of ubiquitous porous materials, such as zeolites, but their application and role in the synthesis of metal-organic frameworks (MOFs) has been comparatively understudied. Here we report a diverse family of anionic MOFs with all frameworks constructed exclusively from the same metal cation and plant-based organic linker—Zr(IV) cations and ellagate anions. Applying the same synthesis conditions but only changing the species of the SDA resulted in 10 novel zirconium ellagate MOFs (denoted SU-103 – SU-112) with varying dimensionality, topologies, Zr(IV) coordination geometries, intermolecular framework interactions, and framework interpenetration. Modern electron diffraction and electron microscopy techniques revealed the location of the SDA molecules in the pores of all MOFs, enabling a detailed study of their interactions. Despite having similar framework compositions, the properties of these MOFs noticeably differ due to the different ammonium SDAs and the unique framework structures obtained. The MOFs demonstrate chemical stability in aqueous media, basic conditions, and concentrated salt solutions, which is attributed to the strong Zr-catecholate chelating interactions consolidating the frameworks. We anticipate these 10 MOFs are only a small portion of a potential plethora of MOFs that could be discovered within this system. This lays the groundwork for the discovery of many other chemically robust structure-directed MOFs made with different cationic SDAs, framework metal cations, as well as other organic linkers with polyanionic functional groups.