A Cu2+ specific metallohydrogel: preparation, multi-responsiveness and pillar[5]arene-induced morphology transformation

A Cu²⁺ specific metallohydrogel was constructed from a terpyridine-based low molecular weight ligand. The metallohydrogel showed multi-responsiveness and its morphology could be transformed by pillararene-based host–guest interaction.

Role of polar solvents for the synthesis of pillar[6]arenes

An efficient procedure for the synthesis of pillar[6]arenes has been developed.

A polycation-induced secondary assembly of amphiphilic calixarene and its multi-stimuli responsive gelation behavior

A calixarene-based supramolecular hydrogel with reversible or irreversible gelation behaviors in response to external stimuli constructed via a hierarchical induced assembly strategy.

Solid-state assembly of carboxylic acid substituted pillar[5]arene and its host–guest complex with tetracaine

The first examples of carboxylic acid substituted pillar[5]arene structures in the form of its inclusion complexes with ethanol and the anesthetic drug tetracaine are reported.

Binding of carboxylatopillar[5]arene with alkyl and aryl ammonium salts in aqueous medium

Alkyl ammonium salts exhibited strong binding with carboxylatopillar[5]arene in aqueous medium which resulted in the formation of pseudo[2]rotaxane and pseudo[3]rotaxane species.

Stimuli-responsive metal-organic frameworks gated by pillar[5]arene supramolecular switches

Spurred on by recent advances in materials chemistry and drug delivery, a new stimuli-responsive theranostic hybrid platform, based on mechanized monodisperse nano metal-organic frameworks (NMOFs) gated by carboxylatopillar[5]arene (CP5) switches with bio-friendly pH-triggered cargo release capabilities, has been constructed for the first time. This nanoscale smart cargo delivery system showed pH- and/or competitive binding agent-triggered controlled cargo release with negligible premature release, large pore sizes for drug encapsulation, low cytotoxicity, good biodegradability and biocompatibility, and potential application in cell imaging, which offers a new tool in targeted drug delivery and the controlled release of therapeutic agents.

Pillar[5]arene-based supramolecular organic frameworks for highly selective CO2-capture at ambient conditions

Low-density, solid-state, porous supramolecular organic frameworks are constructed using pillarenes. The frameworks have a honeycomb-like structure, permanent porosity, high thermal stability, and selective and reversible sorption properties toward CO2. The exceptionally selective CO2-sorption properties (375/1, 339/1) of one framework over N2 and CH4 indicate potential applications in CO2-capture for post-combustion power plants and natural gas sweetening.

Switchable host-guest systems on surfaces

CONSPECTUS: For device miniaturization, nanotechnology follows either the "top-down" approach scaling down existing larger-scale devices or the "bottom-up' approach assembling the smallest possible building blocks to functional nanoscale entities. For synthetic nanodevices, self-assembly on surfaces is a superb method to achieve useful functions and enable their interactions with the surrounding world. Consequently, adaptability and responsiveness to external stimuli are other prerequisites for their successful operation. Mechanically interlocked molecules such as rotaxanes and catenanes, and their precursors, that is, molecular switches and supramolecular switches including pseudorotaxanes, are molecular machines or prototypes of machines capable of mechanical motion induced by chemical signals, biological inputs, light or redox processes as the external stimuli. Switching of these functional host-guest systems on surfaces becomes a fundamental requirement for artificial molecular machines to work, mimicking the molecular machines in nature, such as proteins and their assemblies operating at dynamic interfaces such as the surfaces of cell membranes. Current research endeavors in material science and technology are focused on developing either a new class of materials or materials with novel/multiple functionalities by shifting host-guest chemistry from solution phase to surfaces. In this Account, we present our most recent attempts of building monolayers of rotaxanes/pseudorotaxanes on surfaces, providing stimuli-induced macroscopic effects and further understanding on the switchable host-guest systems at interfaces. Biocompatible versions of molecular machines based on synthetic macrocycles, such as cucurbiturils, pillararenes, calixarenes, and cyclodextrins, have been employed to form self-assembled monolayers of gates on the surfaces of mesoporous silica nanoparticles to regulate the controlled release of cargo/drug molecules under a range of external stimuli, such as light, pH variations, competitive binding, and enzyme. Rotaxanes have also been assembled onto the surfaces of gold nanodisks and microcantilevers to realize active molecular plasmonics and synthetic molecular actuators for device fabrication and function. Pillararenes have been successfully used to control and aid the synthesis of gold nanoparticles, semiconducting quantum dots, and magnetic nanoparticles. The resulting organic-inorganic hydrid nanomaterials have been successfully used for controlled self-assembly, herbicide sensing and detection, pesticide removal, and so forth, taking advantage of the selective binding of pillarenes toward target molecules. Cyclodextrins have also been successfully functionalized onto the surface of gold nanoparticles to serve as recycling extractors for C60. Many interesting prototypes of nanodevices based on synthetic macrocycles and their host-guest chemistry have been constructed and served for different potential applications. This Account will be a summary of the efforts made mainly by us, and others, on the host-guest chemistry of synthetic macrocyclic compounds on the surfaces of different solid supports.

Three-component vesicle aggregation driven by adhesion interactions between Au nanoparticles and polydopamine-coated nanotubes

Large-scale and robust vesicle aggregates were obtained through three-component molecular recognition among cell-sized polymer vesicles, carbon nanotubes and Au nanoparticles driven by adhesion interactions between Au and polydopamine.

Protein surface recognition by calixarenes

The present review summarizes recently developed calixarene derivatives for protein surface recognition which are able to identify, inhibit, and separate specific proteins.

Construction of muscle-like metallo-supramolecular polymers from a pillar[5]arene-based [c2]daisy chain

A muscle-like metallo-supramolecular polymer based on a solvent-driven [c2]daisy chain has been prepared from an amino-modified pillar[5]arene. The integration of terpyridine moieties on both ends of the [c2]daisy chain and the stiff architecture of pillar[5]arene units facilitated the efficient formation of the metallo-supramolecular polymer.