Molecule-Responsive Supramolecular Hydrogel Constructed from Pillar[5]arene Based on Host-Guest System

Abstract

The host-guest interaction was qualified as an ideal drive force to form stable inclusion complexes with macrocyclic host molecules in aqueous solution. Herein, a multi-responsive supramolecular hydrogel was constructed based on a functionalized benzimidazole derivative guest (M) with soluble pillar[5]arene as a host group. The mechanism of hydrogel formation was explored by the 1 H NMR, 2D NOESY and scanning electron microscope (SEM) in depth study. Interestingly, host-guest inclusion, the ordered "exo-wall" π-π interaction and hierarchical stacking of pillar [5]arene was indispensable to obtain the supramolecular hydrogel, which endowed the gel system with response to temperature change/chemical stimuli. Upon addition of competitive guests adiponitrile (ADN)/paraquat (PQ), pillar[5]arene-based hydrogel could be converted into sol. Herein, the organic molecules could be selectively recognized by the hydrogel.

Pillararene‐Based Supramolecular Polymers for Adsorption and Separation

“…The results revealed that SH‐BP5 could not only sensitively respond to temperature and chemical stimulus but also selectively capture competitive guests such as adiponitrile (ADN) and PQ. [ 12 ]…”

“…The results revealed that SH-BP5 could not only sensitively respond to temperature and chemical stimulus but also selectively capture competitive guests such as adiponitrile (ADN) and PQ. [12] Pillararenes containing specific moieties can also serve as guests for constructing supramolecular polymer gels. For instance, Wei and coworkers synthesized a microsphere supramolecular polymer gel (P5BD-DPHB-G) through hostguest and 𝜋•••𝜋 stacking interactions between N-(pyridinium-4-yl)-naphthalimide-pillar [5]arenes (P5BD, host) and 1,4-bisbromohexane functionalized-pillar [5]arenes (DPHB, guest).…”

“…Supramolecular polymers, the elegant combination of supramolecular chemistry with polymer science, have been contemplated as potential candidates for constructing smart adsorbing materials at the molecular level. [1][2][3][4][5] Different from traditional chemical polymers, supramolecular polymers are connected by non-covalent interactions with dynamic DOI: 10.1002/adma.202301721 and reversible properties, including hydrogen bonding, [6][7][8] metal coordination, [9][10][11] 𝜋•••𝜋 stacking, [12,13] electrostatic, [14] and host-guest interactions. [15][16][17][18] Therefore, supramolecular polymers not only possess the advantages of polymeric materials such as good stability and low toxicity, but also show many specific characteristics including selectivity, stimuliresponsibility, and recyclability.…”

Composite Dynamic Hydrogels Constructed on Boronic Ester Cross-Links with NIR-Enhanced Diffusivity

“…The construction of these materials is based on either noncovalent interactions or reversible covalent bonds. Among noncovalent interactions, hydrogen bonding, π–π stacking, hydrophobic interactions, host–guest complexation, , electrostatic interactions, metal coordination, etc. are applied for hydrogel formation.…”