In the daisy-chain supramolecular polymer A shown in the Box, monomeric units contain a dibenzo[24]crown-8 head and a dibenzylammonium stem. Successful complexation of these two moieties to each other has been demonstrated, thus suggesting that their incorporation into a single molecule (B in the Box) should yield materials that are the result of supramolecular polymerization. Previous efforts have failed to produce supramolecular daisy-chain polymers, giving instead the thermodynamically favored cyclic dimer (C in the Box) as the self-assembled supramolecular system.

In a renewed attempt to obtain supramolecular daisy-chain polymers, we are targeting monomeric structures that would disfavor the formation of the cyclic dimers either a) entropically, by using a long rigid spacer between the two binding sites, or b) enthalpically, through the introduction of an extremely bulky pentiptycene spacers that would prohibit dimerization sterically. To probe these hypotheses, we are pursuing the synthesis of compounds shown in D in the Box through the use of Sonogashira couplings as the key carbon-carbon bond forming reactions. The complexation of these new systems has been examined by NMR spectroscopy and mass spectrometry. Where applicable, polymer characterization techniques have also been employed. The results of these investigations will be presented in the poster.