Host-guest properties of pagoda[4]arene with α,ω-dibromoalkanes and their self-assembled linear supramolecular polymer driven by guest halogen–halogen interactions

Herein we report the host-guest interactions of pagoda[4]arene with various α,ω-dibromoalkanes. The guest encapsulation properties were probed by ¹H NMR titration and isothermal titration calorimetry (ITC) experiments. Unlike pillararenes, the deeper cavity of pagoda[4]arene shows higher affinity toward longer straight-chain molecules with 1:1 host-to-guest stochiometric ratio of complexation. In addition, the formation of the self-assembled supramolecular polymer driven by guest halogen-halogen interactions in solution was demonstrated by diffusion-ordered spectroscopy (DOSY), ITC, and dynamic light scattering (DLS) measurements. From the ITC dilution experiments, we found that the supramolecular polymer dissociation process is mainly entropically driven (TΔS = 64.00 kJ mol⁻¹) and enthalpically disfavored (ΔH = 43.91 kJ mol⁻¹).