We have established a new method of supramolecular polymerization promoted and controlled by self-sorting recently. Although cucurbit[8]uril(CB[8])-based π-π interaction has been successfully introduced to drive supramolecular polymerization, it remains unclear if there exists cooperative effect and how it is influenced and adjusted by structural variations. This research is aimed to investigate the cooperative effect of CB[8]-based π-π interaction. For this purpose, we design and synthesize a series of model compounds containing the benzyl moiety with various positive charged side groups. In this way, hydrophobicity and steric factor of positive charged moieties can influence the cooperative effect of CB[8]-based π-π interaction and then result in relative changes of stepwise affinities (corresponding to K1 and K2), thus making binding modes divided into three types. For the first mode (K2 &gt;&gt; K1), strong cooperative effect can lead to the direct formation of ternary complexes; for the second mode (K2 ≈ K1), weak cooperative effect can allow the coexistence of binary and ternary complexes during the binding process; for the third mode (K2 &lt;&lt; K1), a stable binary complex can be formed due to the absence of this effect and even suppress the second step binding. This line of research reveals the fundamental influence of cooperative effect in the complexation between CB[8] and guest molecules, which provides guidance for tuning CB[8]-based π-π interactions as driving forces for supramolecular polymerization.

Cooperative effect of cucurbit[8]uril-based π-π interaction

249th National Meeting (2015)

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