Three protocols for the formation of a [3]pseudorotaxane via orthogonal cryptand-based host-guest recognition and coordination-driven self-assembly

Construction of Supramolecular Polymers with Different Topologies by Orthogonal Self-Assembly of Cryptand-Paraquat Recognition and Metal Coordination

Recently, metal-coordinated orthogonal self-assembly has been used as a feasible and efficient method in the construction of polymeric materials, which can also provide supramolecular self-assembly complexes with different topologies. Herein, a cryptand with a rigid pyridyl group on the third arm derived from BMP32C10 was synthesized. Through coordination-driven self-assembly with a bidentate organoplatinum(II) acceptor or tetradentate Pd(BF4)2•4CH3CN, a di-cryptand complex and tetra-cryptand complex were prepared, respectively. Subsequently, through the addition of a di-paraquat guest, linear and cross-linked supramolecular polymers were constructed through orthogonal self-assembly, respectively. By comparing their proton nuclear magnetic resonance (1H NMR) and diffusion-ordered spectroscopy (DOSY) spectra, it was found that the degrees of polymerization were dependent not only on the concentrations of the monomers but also on the topologies of the supramolecular polymers.

Theoretical Prediction on a Novel Reduction-Responsive Nanoring Having a Disulfide Group for Facile Encapsulation and Release of Fullerenes C60 and C70

In this work, a novel reduction-responsive disulfide bond-containing cycloparaphenylene nanoring molecule (DSCPP) with a pyriform shape has been designed. In addition, the interactions between the designed nanoring (host) and fullerenes C₆₀ and C₇₀ (guests) were investigated theoretically at the M06-2X/6-31G(d,p) and M06-L/MIDI! levels of theory. By analyzing geometric characteristics and host-guest binding energies, it is revealed that the designed DSCPP is an ideal host molecule of guests C₆₀ and C₇₀. DSCPP presents excellent elastic deformation during the encapsulation of C₆₀ and C₇₀. The high binding energies suggest that both DSCPP⊃C₆₀ and DSCPP⊃C₇₀ (∼92 and 118 kJ·mol^-1 at the M06-2X/6-31G(d,p) level of theory) are stable host-guest complexes, and the guest C₇₀ is more strongly encapsulated than C₆₀ in the gas phase. The thermodynamic information indicates that the formation of the two host-guest complexes is thermodynamically spontaneous. In addition, the frontier molecular orbital (FMO) features and intermolecular weak interaction region between DSCPP and fullerenes gusts are discussed to further understand the structures and properties of the DSCPP⊃fullerene systems. Finally, the ring-opening mechanism of the DSCPP under reduction conditions is investigated.

Self-healing polymer materials constructed by macrocycle-based host-guest interactions

Self-healing polymers, which can spontaneously recover themselves after being ruptured, result in enhanced lifetimes for materials and open up a fascinating direction in material science. Macrocycle-based host-guest interactions, one of the most crucial non-covalent interactions, play a key role in self-healing material fabrication. This review aims to highlight the very recent and important progress made in the area of self-healing polymer materials by focusing on cyclodextrins (CDs), crown ethers, cucurbit[n]urils (CBs), calix[n]arenes and pillar[n]arenes with special guest groups and tailored structures. In addition, we also propose future research directions and hope that this review can in a way reflect the current situation and future trends in this developing area.

Mechanically Linked Poly[2]rotaxanes Constructed via the Hierarchical Self-Assembly Strategy

Mechanically linked poly[2]rotaxanes have been successfully constructed via the hierarchical self-assembly strategy. The integration of two noninterfering noncovalent recognition motifs facilitates chain extension of the B21C7-based [2]rotaxane monomer, demonstrating the capabilities to form self-standing films with preferable transparency and softness.

A responsive supramolecular metallogel constructed by coordination-driven self-assembly of a crown ether-based [3]pseudorotaxane and a diplatinum(ii) acceptor

A stimuli-responsive supramolecular polymeric metallogel was prepared by orthogonal coordination-driven self-assembly of a crown ether-based [3]pseudorotaxane and a 180° organic di-Pt(ii) acceptor.

The exchangeable self-assembly behaviour of bis-pseudorotaxanes with metallo-bisviologens (CH3PyTpyFeTpyPyCH34+) and crown ether (Tpy = 2,2′:6′,2′′-terpyridine)

Two different terpyridine chelated Fe²⁺ complexes which contain two methyl-pyridinium salts could be self-assembled with dibenzo-24-crown-8 ether to generate exchangeable double metallo-pseudorotaxanes.

PO functional group-containing cryptands: from supramolecular complexes to poly[2]pseudorotaxanes

Host–guest systems based on PO functional group-containing cryptands and the corresponding supramolecular poly[2]pseudorotaxanes with different shapes were constructed successfully.

Well-defined supramolecular polymers based on orthogonal hydrogen-bonding and host–guest interactions

Two architecturally controlled supramolecular polymers have been fabricated via the concurrent integration of orthogonal non-covalent recognition motifs, demonstrating significant chain topological-dependent supramolecular polymerization behaviors.