Stimuli‐Responsive Supramolecular Gels Constructed by Hierarchical Self‐Assembly Based on Metal‐Ligand Coordination and Host–Guest Recognition

Abstract

Metal-ligand coordination and host-guest recognition are introduced into the hybrid system in order to prepare supramolecular gels, which can be responsive to multiple external stimuli such as metal ions, competitive guest/host molecules, and oxidants. To this end, the triangular terpyridine-based metallocycles functionalized with 1-adamantyl and ferrocenyl groups are constructed through self-assembly, and further used as supramolecular cross-linkers for gelation of β-CD-containing copolymers. Their gelation and stimuli-response tests are discussed, and an application of the metallotriangles for serving as supramolecular glue is demonstrated through a series of adhesion experiments. This approach enables facile access to construction of multifunctional metallosupramolecules as well as functional hybrid materials.

Functional Supramolecular Polymeric Networks: The Marriage of Covalent Polymers and Macrocycle-Based Host–Guest Interactions

“…Incorporation of metallosupramolecular structures into polymer matrices has allowed access to hybrid materials endowed not only with the tunable viscoelastic properties characteristic of organic polymers, but also ones with unique features that originate from the metal centers. ,− Chan and co-workers reported a series of metallo-SPNs constructed from β-CD-containing copolymers and triangular metallocycles functionalized with Ad and Fc guest moieties . As shown in Figure , the Ad- or Fc-modified triangular terpyridine of generalized structure 108 was found to coordinate Fe­(II) and Zn­(II) ions to form triangular metallocycles (shown schematically as 109 ).…”

“…Also shown in schematic form is the SPN gel 111 constructed through hierarchical self-assembly driven by metal–ligand complexation and β-CD/Ad or β-CD/Fc host–guest interactions. Reproduced with permission from ref . Copyright 2018 John Wiley and Sons.…”

“…114,293−303 Chan and co-workers reported a series of metallo-SPNs constructed from β-CD-containing copolymers and triangular metallocycles functionalized with Ad and Fc guest moieties. 304 As shown in Figure 32, the Ad-or Fc-modified triangular terpyridine of generalized structure 108 was found to coordinate Fe(II) and Zn(II) ions to form triangular metallocycles (shown schematically as 109). Host−guest interactions between 108 and PNIPAM-or poly(acrylamide) (PAAM)-based β-CD-containing copolymers 110 gave rise to a series of supramolecular polymeric gels, 111, which proved responsive to various external stimuli.…”

Lanthanide-Directed Luminescent “Soft” Coordination Polymer Gels: White Light Emission, Anticounterfeiting, and Thin-Film-Based Sensing

“…For example, chameleons adopt various color hues to escape harm from their environment. Therefore, the design and development of external stimuli-responsive (under light, pressure, humidity, pH, electrical input, and redox) smart soft materials with targeted responses is an appealing and challenging endeavor. − Numerous smart biomimetic materials have been reported with external stimuli-responsive properties. , Supramolecular coordination polymer gels (CPGs) are among such materials due to the presence of dynamic interactions such as hydrogen bonding, π–π interactions, dipole–dipole interaction, and so forth that can be destroyed and regenerated under the exposure of various external stimuli. , Building upon our previous mechanoresponsive work, we sought to fabricate light-responsive multifunctional CPG materials …”

“…7,8 Supramolecular coordination polymer gels (CPGs) are among such materials due to the presence of dynamic interactions such as hydrogen bonding, π−π interactions, dipole−dipole interaction, and so forth that can be destroyed and regenerated under the exposure of various external stimuli. 9,10 Building upon our previous mechanoresponsive work, we sought to fabricate light-responsive multifunctional CPG materials. 11 Light-emitting materials are increasingly being explored due to their applications in displays and devices.…”