Peifa Wei

Responsive supramolecular polymer metallogel constructed by orthogonal coordination-driven self-assembly and host/guest interactions.

An emerging strategy for the fabrication of advanced supramolecular materials is the use of hierarchical self-assembly techniques wherein multiple orthogonal interactions between molecular precursors can produce new species with attractive properties. Herein, we unify the spontaneous formation of metal-ligand bonds with the host/guest chemistry of crown ethers to deliver a 3D supramolecular polymer network (SPN). Specifically, we have prepared a highly directional dipyridyl donor decorated with a benzo-21-crown-7 moiety that undergoes coordination-driven self-assembly with a complementary organoplatinum acceptor to furnish hexagonal metallacycles. These hexagons subsequently polymerize into a supramolecular network upon the addition of a bisammonium salt due to the formation of [2]pseudorotaxane linkages between the crown ether and ammonium moieties. At high concentrations, the resulting 3D SPN becomes a gel comprising many cross-linked metallohexagons. Notably, thermo- and cation-induced gel-sol transitions are found to be completely reversible, reflecting the dynamic and tunable nature of such supramolecular materials. As such, these results demonstrate the structural complexity that can be obtained when carefully controlling multiple interactions in a hierarchical fashion, in this case coordination and host/guest chemistry, and the interesting dynamic properties associated with the materials thus obtained.

A Novel Diblock Copolymer with a Supramolecular Polymer Block and a Traditional Polymer Block: Preparation, Controllable Self-Assembly in Water, and Application in Controlled Release

A novel diblock copolymer with a hydrophobic supramolecular polymer block and a hydrophilic traditional polymer block has been prepared. Control over the chain length ratio of the two blocks is obtained by simply changing the concentration proportion of the monomer of the supramolecular polymer block to the traditional polymer block in solution. When the chain length ratio of the two blocks is changed, the formation of various self-assembly morphologies is achieved.

A Discrete Amphiphilic Organoplatinum(II) Metallacycle with Tunable Lower Critical Solution Temperature Behavior

Oligo(ethylene glycol) (OEG)-decorated supramolecular assemblies are distinguished by their neutral character and macroscopic temperature-sensitive phase transition behavior. OEG functionalization is an emerging strategy to obtain thermoresponsive macrocyclic amphiphiles, although known methods organize the hydrophilic and hydrophobic segments by covalent bonding. Coordination-driven self-assembly offers an alternative route for organizing OEG-functionalized precursors into nanoscopic architectures, resulting in well-defined metallacycle cores surrounded by hydrophilic scaffolds to impart overall amphiphilic character. Here a tri(ethylene glycol)-functionalized thermosensitive amphiphilic metallacycle was prepared with high efficiency by means of the directional-bonding approach. The ensembles thus formed showed good lower critical solution temperature behavior with a highly sensitive phase separation and excellent reversibility. Moreover, the clouding point decreased with increasing metallacycle concentration and addition of K(+).

pH-responsive assembly and disassembly of a supramolecular cryptand-based pseudorotaxane driven by π–π stacking interaction

Driven by π-π stacking interaction, a supramolecular cryptand-based [2]pseudorotaxane was formed and its formation was demonstrated to be pH-responsive.

[2]Pseudorotaxanes based on the recognition of cryptands to vinylogous viologens.

Host-guest complexation between two crown ether-based cryptands and two vinylogous viologens has been studied. Formation of [2]pseudorotaxanes from a dibenzo-24-crown-8-based cryptand and these vinylogous viologens can be reversibly controlled by adding and removing potassium cation in acetone. Furthermore, the complexation between a bis(m-phenylene)-32-crown-10-based cryptand and a vinylogous viologen exhibits a high association constant, 1.18 × 10(6) M(-1) in acetone, and leads to the formation of a supramolecular poly[2]pseudorotaxane in the solid state.

Two 2 : 3 copillar[5]arene constitutional isomers: syntheses, crystal structures and host–guest complexation of their derivatives with dicarboxylic acid sodium salts in water

Two 2 : 3 copillar[5]arene constitutional isomers were prepared and host-guest complexation of their derivatives with dicarboxylic acid sodium salts in water was investigated.

Pseudorotaxanes from self-assembly of two crown ether-based cryptands and a 1,2-bis(pyridinium) ethane derivative

Pseudorotaxanes from self-assembly of two crown ether-based cryptand wheels and a 1,2-bis(pyridinium) ethane derivative axle were prepared.

Metallosupramolecular poly[2]pseudorotaxane constructed by metal coordination and crown-ether-based molecular recognition.

A novel bis(m-phenylene)-32-crown-10 derivative bearing two π-extended pyridyl groups was synthesized, and its host-guest complexation with a paraquat derivative to form a threaded [2]pseudorotaxane was studied. Subsequently, a poly[2]pseudorotaxane was constructed with a metallosupramolecular polymer backbone via metal coordination, which was comprehensively confirmed by the combination of (1)H NMR, (31)P{(1)H} NMR, DOSY NMR, DLS, and EDX techniques.

Benzo-21-crown-7-based [1]rotaxanes: Syntheses, X-ray crystal structures, and dynamic characteristics

Two B21C7-based [1]rotaxanes were synthesized in high yields by means of copper(II)-mediated Eglinton coupling and a subsequent Pd/C-catalyzed reduction under H2. X-ray single-crystal analysis shows that [1]rotaxane takes on a self-entangled conformation, wherein the macrocycle is threaded by its own tail. Moreover, it was found that [1]rotaxane with a flexible skeleton had more rotational motions than that of one with a rigid skeleton.

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

A novel bis(m-phenylene)-32-crown-10-based cryptand 1 with a pyridine nitrogen atom outside on the third arm was designed and synthesized. Subsequently, host-guest complexation between cryptand 1 and a selection of bipyridinium guests has been studied. More interestingly, the [3]pseudorotaxane 2 is a superset of 5(2) was obtained in three methods by utilizing the noninterfering orthogonal nature of coordination-driven self-assembly and host-guest interactions.