Pillar[5]arene based supramolecular prodrug micelles with pH induced aggregate behavior for intracellular drug delivery

A novel type of dual pH-responsive supramolecular prodrug micelles based on host-guest interactions of water-soluble pillar[5]arene (WP5) and methyl viologen functioned doxorubicin (MV-DOX) was prepared. It was found that the prodrug micelles could be aggregated upon acidic condition, which led to enhanced accumulation and better therapy effect.

Solvent effects and driving forces in pillararene inclusion complexes

Pillararenes, a recently discovered class of aromatic macrocycles, form inclusion complexes with a large number of guest molecules, but not much is known about the driving forces of complexation, including the role of the solvent. We have measured the binding thermodynamics for a small number of model complexes in several solvents and used computational chemistry to rationalize the obtained results and identify the driving forces of complexation. Favorable electrostatic interactions between the host and guest are obtained when the charge distribution in the guest matches the negative electrostatic potential in the cavity of the pillararene. Polar guests, however, also interact strongly with polar solvents, thereby shifting the complexation equilibrium away from the complex. The shape of the solvent molecules is another important factor as some solvents are sterically hindered from entering the pillararene cavity. By changing solvent from acetonitrile to o-xylene the binding constant in one case increased more than 4 orders of magnitude. Even electrostatically similar solvents such as o-xylene and p-xylene have very different impacts on the binding constants due to their different abilities to fit into the cavity. The study illustrates the importance of taking into account the interactions between the solvent and the complexing species in the investigation and design of molecular host:guest systems.

Photo-responsive reversible assembly of gold nanoparticles coated with pillar[5]arenes

Gold nanoparticles stabilized by sulfhydryl functionalized pillar[5]arenes were successfully prepared. When they complex with anthracene derivatives on their surfaces, they can reversibly aggregate and disassemble based on photocycloaddition of anthracene.

A [2]rota[2]catenane, constructed from a pillar[5]arene-crown ether fused double-cavity macrocycle: synthesis and structural characterization

A [2]rota[2]catenane, based on a pillar[5]arene-crown ether fused bicycle, was constructed and its structure was determined crystallographically.

Supramolecular hydrophobic guest transport system based on pillar[5]arene

A pillar[5]arene-based bioactive guest loading system was developed, which increased the solubility of norharmane in aqueous medium.

Molecular binding behavior of bipyridium derivatives by water-soluble carboxylato-biphen[3]arene

Complexation of paraquat derivatives and bis(N-mono-substituted bipyridine) cations by a negatively charged carboxylato-biphen[3]arene in water is described.

pH-Responsive supramolecular vesicles assembled by water-soluble pillar[5]arene and a BODIPY photosensitizer for chemo-photodynamic dual therapy

Supramolecular vesicles assembled by water-soluble pillar[5]arene and a BODIPY photosensitizer are constructed for chemo- and photodynamic dual therapy.

Supramolecular assembly-induced yellow emission of 9,10-distyrylanthracene bridged bis(pillar[5]arene)s

Newly synthesized DSA-bridged bis(pillar[5]arene)s with AIE properties form linear supramolecular polymers upon binding to a neutral guest linker, exhibiting supramolecular assembly-induced yellow fluorescence emission.

Host–guest complexation of pillar[6]arenes towards neutral nitrile guests

The binding behavior of a series of nitrile derivatives by ethylated pillar[6]arene is described; this work represents the first example of complexation of neutral guests by pillar[6]arenes.

Novel pseudo[2]rotaxanes constructed by the self-assembly of dibenzyl tetramethylene bis-carbamate derivatives and per-ethylated pillar[5]arene

Novel pseudo[2]rotaxanes based on per-ethylated pillar[5]arene and neutral guests G1/G7 were successfully constructed. Particularly, the pseudo[2]rotaxane constructed from per-ethylated pillar[5]arene and G7 showed photoresponsive properties.

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.

Structural study of a small molecule receptor bound to dimethyllysine in lysozyme

Lysine is a ubiquitous residue on protein surfaces. Post translational modifications of lysine, including methylation to the mono-, di- or trimethylated amine result in chemical and structural alterations that have major consequences for protein interactions and signalling pathways. Small molecules that bind to methylated lysines are potential tools to modify such pathways. To make progress in this direction, detailed structural data of ligands in complex with methylated lysine is required. Here, we report a crystal structure of p-sulfonatocalix[4]arene (sclx₄) bound to methylated lysozyme in which the lysine residues were chemically modified from Lys-NH₃⁺ to Lys-NH(Me₂)⁺. Of the six possible dimethyllysine sites, sclx₄ selected Lys116-Me₂ and the dimethylamino substituent was deeply buried in the calixarene cavity. This complex confirms the tendency for Lys-Me₂ residues to form cation-π interactions, which have been shown to be important in protein recognition of histone tails bearing methylated lysines. Supporting data from NMR spectroscopy and MD simulations confirm the selectivity for Lys116-Me₂ in solution. The structure presented here may serve as a stepping stone to the development of new biochemical reagents that target methylated lysines.

The marriage of endo-cavity and exo-wall complexation provides a facile strategy for supramolecular polymerization

The marriage of exo-wall interactions and endo-cavity inclusion provides a new strategy for the construction of supramolecular polymers from unfunctionalized neutral receptors.

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

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

Molecular binding behaviors and thermodynamics of ferrocenyl dimethylaminium derivatives by anionic pillar[5]arene

A novel anionic water-soluble pillar[5]arene (4C-WP5A) was synthesized via a convenient synthetic strategy of the direct cyclization of a functionalized hydroquinone monomer.

Reversible formation of supramolecular polymer networks via orthogonal pillar[10]arene-based host–guest interactions and metal ion coordinations

Reversible supramolecular polymer networks were constructed by orthogonal pillar[10]arene-based host–guest molecular recognition, terpyridine–Zn²⁺, and carbene–Ag⁺ coordinations.

A cross-linked supramolecular polymer constructed from pillar[5]arene and porphyrine via host–guest interactions

A novel supramolecular polymer, DMeP5@TImPor, was successfully constructed via host–guest interactions between the host molecule, bis-(methoxy-pillar[5]arene) (DMeP5), and the guest molecule, 5,10,15,20-tetrakis{butoxy-4-(1H-imidazol-1-yl)}porphyrine (TImPor).

Synthesis, binding and self-assembly properties of a well-defined pillar[5]arene end functionalised polydimethylacrylamide

The synthesis, binding and self-assembly properties of a well-defined pillar[5]arene end functionalised polydimethylacrylamide are reported.

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.

Formation of fluorescent supramolecular polymeric assemblies via orthogonal pillar[5]arene-based molecular recognition and metal ion coordination

A fluorescent supramolecular polymer was efficiently constructed by pillar[5]arene-based host–guest molecular recognition and zinc ion coordination.

Optical spectroscopic studies on the complexation of stilbazolium dyes with a water soluble pillar[5]arene

The host–guest interactions of carboxylato-pillar[5]arene (WPA5) and three stilbazolium dyes were studied by optical spectroscopy. A fluorescence indicator displacement based on WPA5 was shown to detect paraquat in aqueous solution.

Pillar[6]arene-valved mesoporous silica nanovehicles for multiresponsive controlled release

The synthesis and host-guest chemistry of pillararene (PA) derivatives are a hot research topic, and the applications of PAs in relevant research fields are essential to explore. Carboxylate-substituted pillar[6]arene (CPA[6])-valved mesoporous silica nanoparticles (MSNs) functionalized with dimethylbenzimidazolium (DMBI) and bipyridinium (BP) stalks were constructed, respectively, for multiresponsive controlled release. CPA[6] encircled the DMBI or BP stalks to develop supramolecular nanovalves for encapsulation of cargo within the MSN pores. The release of cargo was triggered by acidic pH or competitive binding for the dethreading of CPA[6] and the opening of the nanovalves; moreover, coordination chemistry is the first strategy to activate CPA nanovalves by metal chelating with the carboxylate groups of CPA for cargo release. The controlled release of the CPA[6]-valved MSN delivery systems can meet diverse requirements and has promising biological applications in targeted drug therapy.

A novel fluorescent probe for detecting paraquat and cyanide in water based on pillar[5]arene/10-methylacridinium iodide molecular recognition

A novel fluorescent probe for detecting paraquat and cyanide in water based on pillar[5]arene/10-methylacridinium iodide molecular recognition is reported.

Protein assembly mediated by sulfonatocalix[4]arene

The binding of anionic p-sulfonatocalix[4]arene to cationic lysozyme results in self assembly and the formation of protein tetramer chains, as revealed by X-ray crystallography.