Three Distinct Equilibrium States via Self-Assembly: Simple Access to a Supramolecular Ion-Controlled NAND Logic Gate

During
the past several decades, considerable effort has focused
on self-assembled systems. However, most work has been directed toward
understanding the equilibrium between two major chemical entities,
namely the dissociated components and the corresponding associated
complex. While there are quite a few examples of ‘multiresponsive’
materials, control over ‘multistate’ materials has proved
difficult to achieve. Here, we report the formation and the interplay
of a self-assembled calix[4]­pyrrole array that exhibits three limiting
forms, namely a 1:1 self-assembled oligomer, a 2:1 capsule, and the
corresponding monomers. Interconversion between these states may be
controlled by using the tetraethylammonium cation (TEA+) and/or iodide anion (I–) as chemical inputs.
The combination of self-assembly and ion-based control may be used
to create systems that display NAND logic behavior. The system outputs
have been confirmed by a variety of analytic methods, including UV–vis
and 2D 1H DOSY, NOESY NMR spectroscopy, scanning electron
microscopy, and single crystal X-ray diffraction analyses.