The Organic Secondary Building Unit: Strong Intermolecular pi Interactions Define Topology in MIT-25, a Mesoporous MOF with Proton-Replete Channels

The structure-directing role of the inorganic sec-ondary building unit (SBU) is key for determining the topology of metal-organic frameworks (MOFs). Here, we show that organic building units relying on strong π interactions that are energetical-ly competitive with the formation of common inorganic SBUs, and can play a role in defining topology. We demonstrate the importance of the organic SBU in the formation of Mg2H6(H3O)(TTFTB)3, a mesoporous MOF with the new ssp topology. A delocalized electronic hole is critical in the stabiliza-tion of the TTF triad organic SBUs and exemplifies a design prin-ciple for future MOF synthesis