s Efficient Control of the Formation of Pillar[5]arene-based Supramolecular Polymers

Background: The design and preparation of functional pillar[n]arene-based supramolecular polymers have attracted extensive attention due to their wide range of applications. Objective and Methods: Based on the synergistic effects of non-covalent interactions, including hydrogen bonds and host-guest interaction, an amphiphilic pillar[5]arene 1 with two terminated acid chains was designed, and its self-assembly properties were investigated by ¹HNMR, TEM, SEM and UV-Vis. Results: The pillar[5]arene 1 can form a self-inclusion complex, whose carboxyl groups are locked on the surface of the cavity at low concentration (<4.5 mM) in chloroform. Interestingly, when competitive guest dihaloalkanes, such as α,ω-diiodobutane (DIB), α,ω-dibromobutane (DBB) and α,ω-dichlorobutane (DCB), were added, supramolecular polymers were immediately obtained and precipitated. Their critical precipitation concentration (CPC) were calculated as 1 mM, 3 mM and 5 mM for DIB, DBB and DCB, respectively. Moreover, tuning the solvent, concentration and guests can reversibly control their polymerization. Conclusion: This study provided an efficient method for the preparation of pillar[5]arene-based supramolecular polymers, which have the potential for the separation or purification of the dihaloalkanes.