Controlling Structure Beyond the Initial Coordination Sphere: Complexation-Induced Reversed Micelle Formation in Calix[4]pyrrole-Containing Diblock Copolymers.

A diblock copolymer containing a strapped calix[4]pyrrole-based ion pair recognition subunit has been synthesized via RAFT polymerization. As prepared, the polymer is hydrophobic and devoid of any particular morphological form. However, upon ion pair complexation, the copolymer self-assembles to generate reverse micelles in organic media. The reverse micelles formed in this way may be used to extract alkali cation and cesium halide anion salts from an aqueous source into an organic receiving phase. The polymer proved more effective as an extractant than the corresponding free ion pair receptor.

A Dual-Responsive Bola-Type Supra-amphiphile Constructed from a Water-Soluble Calix[4]pyrrole and a Tetraphenylethene-Containing Pyridine Bis-N-oxide.

Complexation between a water-soluble calix[4]pyrrole and a ditopic pyridine N-oxide derivative in aqueous media produces a bola-type supra-amphiphile that self-assembles to produce higher order morphologies, including multilamellar vesicles and micelles depending on the pH. The present bola-type supra-amphiphile exhibits strong fluorescence due to structural changes and aggregation induced by host-guest complexation. The resulting structures may be used to recognize, encapsulate, and release non-fluorescent, water-soluble small molecules.

Understanding the Molecular-Level Interactions of Glucosamine-Glycerol Assemblies: A Model System for Chitosan Plasticization.

Glycerol is the most widely used plasticizer for the biopolymer chitosan. However, there remains a lack of understanding of the molecular-level interactions between chitosan and glycerol. Here, we describe an in-depth spectroscopic study of the intermolecular interactions between the monomeric repeating unit of chitosan, glucosamine, and the plasticizer glycerol. Infrared and nuclear magnetic resonance spectroscopy were used to probe glucosamine assembly at high and low concentrations to establish diagnostic signals for intra- and intermolecular glucosamine interactions. Systematic addition of glycerol was found to disrupt intramolecular glucosamine hydrogen bonds and promote glucosamine self-assembly. Furthermore, we observed a significant preference for glycerol binding to the amine functionality of glucosamine. These findings indicate that the plasticization of chitosan with glycerol requires a specific binding motif and likely occurs via the gel theory mechanism.