Use of supramolecular host-guest chemistry to mediate guest chemical reactivity is an exciting field of research, aiming to mimic and understand enzyme activity. The Raymond group has developed a series of self-assembling homochiral supramolecular M4L6 tetrahedron capable of acting as hosts for a variety of monocationic1 and neutral2guest molecules (Figure 1).Figure 1. Left) Representation of a M4L6assembly with only one ligand shown for clarity. (Right) A space-filling model of the assembly viewed toward a 3-fold axis.Our recent work shows that the hydrophobic cavity of the self-assembled host is able to thermodynamically favor encapsulation of cationic guests that are stabilized by cation-p interaction with six naphthalene spacers.3 This host also shows substrate size restriction, which only allows substrates below a certain size threshold to be encapsulated and undergo catalysis.3To overcome this limitation, we are interested in expanding reactivity and catalysis to the exterior surface of the host molecule. Preliminary result shows that this idea is highly feasible. For example, we have shown that we can selectively locate cationic group on the aperture of the host tetrahedron to form a dicationic dangling host-guest complex. Moreover, introducing a tertiary amine moiety nearby one face of the cluster (surrounded by three naphthalene functionalities) results in formation of an ammonium ion in basic condition. The design and the characterization of the above system will be discussed.Parac, T. N.; Caulder, D. L.; Raymond, K. N. J. Am. Chem. Soc. 1998, 120, 8003.Biros, S. M.; Bergman, R. G.; Raymond, K. N. J. Am. Chem. Soc. 2007, 129, 12094.Pluth, M. D.; Bergman, R. G.; Raymond, K. N. Acc. Chem. Res. 2009, 42, 1650.

Exploration of reactivity on the aperture of a self-assembly supramolecular cluster

248th National Meeting (2014)

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