There is a considerable interest in dynamic materials featuring modular components with nano-scale dimensions and controlled responsiveness to external stimuli. Supramolecular polymers are a class of materials that fulfill nicely all these conditions. Here, we present a family of host-guest supramolecular polymers that combine the outstanding complexing properties of tetraphosphonate cavitands toward N-methylpyridinium guests with molecular switching. The designed monomer is a cavitand featuring four inward facing P=O groups at the upper rim and a single N-methylpyridinium unit at the lower rim, forming instantaneously a polymeric species in solution thanks to the high complexation constants measured for these host-guest interactions. This system has been analyzed by NMR spectroscopic and electrochemical techniques. In order to interpret the results of diffusion-sensitive experiments, we took advantage of the X-ray crystal structure obtained for the polymeric species and developed an original treatment of the PGSE data by non-linear fitting. The analysis of the experimental data identified an isodesmic polymerization model at monomer concentration below 20 mM, driven by intrachain host-guest interactions, and an additional level of tetrameric bundle aggregation above 20 mM, due to interchain dipolar and quadrupolar interactions. Two orthogonal disassembly procedures have been implemented: electrochemical reduction for the linear chains and solvent-driven dissolution for the bundles.
Hierarchical Self-assembly and Controlled Disassembly of a Cavitand-based Host-Guest Supramolecular Polymer / Zuccaccia, Daniele; Dalcanale, Enrico; Macchioni, Alceo; Zuccaccia, Cristiano; Credi, Alberto; Semeraro, Monica; Geremia, Silvano; De Zorzi, Rita; Pinalli, Roberta. - In: POLYMER CHEMISTRY. - ISSN 1759-9954. - 12(2021), pp. 389-401. [10.1039/D0PY01483D]
|Appare nelle tipologie:||1.1 Articolo su rivista|