The cover picture shows the construction of novel supramolecular prodrug micelles based on the host-guest interaction of water-soluble pillar[6]arene (WP6) and doxorubicin (DOX)-based drug-drug conjugate (G). Herein, the release rate of DOX from these supramolecular micelles is approximate to 100% within 30 min at pH 5.5 by simulating the endo-lysosomal environment. Significantly, intracellular localization experiments demonstrated that these supramolecular micelles, taken up by cancer cells via endocytosis, can lead to efficient DOX accumulation in SKOV3 cancer cells, implying its promising future for cancer therapy. More details are discussed in the article by Hu et al. on page 329–334.

This review outlines the range and perspectives of the thermodynamic characteristics of pillar[n]arenes in comparison with other successful cavitands, such as cyclodextrins and cucurbit[n]urils.

The marriage of supramolecular metallic nanostructures including metallic macrocycles, MOFs, and metal nanoparticles with pillararene-based host-guest systems is leading to the birth of novel hybrid martials, which combine or enhance the characteristics of these two entities.

The construction of novel supramolecular prodrug micelles based on the host-guest interaction of WP6 and doxorubicin (DOX)-based drug-drug conjugate (G) is reported, and the release rate of DOX from these supramolecular micelles is approximate to 100% within 30 min at pH 5.5 by simulating the endo-lysosomal environment. Significantly, intracellular localization experiments demonstrated that these supramolecular micelles, taken up by cancer cells via endocytosis, can lead to efficient DOX accumulation in SKOV3 cancer cells, implying its promising future for cancer therapy.

The complexation of four neutral guest molecules containing carbon-oxygen double bonds, i.e., 1,6-diacetoxyhexane (1), dimethyl hexanedioate (2), hexanal (3), and 2-hexanone (4), by per-ethylated pillar[5]arene is reported. These guests show remarkably different binding affinities. For example, ester 1 could be fully engulfed by the host cavity to form a [2]pseudorotaxane-type inclusion complex, while for 2, no obvious host-guest interaction was observed.

Pillar[6]arenes have been demonstrated to be selectively synthesized in the presence of templated naphthalene diimides.

A novel pH-responsive [2]pseudorotaxane based on ethylated pillar[6]arene and bis(1,2,3-triazolium)butane cation was constructed. The dethreading and rethreading could be reversibly controlled by adding base and acid, i.e., the deprotonation and reprotonation of the guest. In contrast, such responsible switching behavior does not occur for the complexation between the guest and ethylatedpillar[5]arene, since both the cationic axle and the deprotonated one can be strongly bound by ethylated pillar[5]arene. Furthermore, the bis(1,2,3-triazolium)butane⊂pillar[6]arene-[2]pseudorotaxane can also disassemble upon the addition of competitive ethylated pillar[5]arene.

A systematic research of the structural characterization and the host-guest binding abilities between three types of pillar[5]arenes is carried out. Their symmetry of structures and complexation behaviour are affected by different substituents or bound guests in the cavity.

DEP[6] and CB[7] could be applied to tune the fluorescence of dye 1.

One phosphine oxide-based pillar[5]arene 1a and two novel phosphorous-based pillar[5]arenas 1b and 1c were synthesized for use as extractants in solvent extraction of UO₂²⁺. The results from host-guest interactions pertinent to the extracted complexes of 1a–1c revealed a significant difference in complexation capability between 1a and 1b (or 1c) by using ¹H NMR, ³¹P NMR and FT-IR techniques. The extraction of UO₂²⁺ in separate extraction system and in simulated nuclear industry effluent containing 12 competing ions demonstrated the superior efficiency and selectivity of 1a towards UO₂²⁺ over other cations in acidic feed. Log-log plot analysis indicated the 1:1 stoichiometry (ligand/metal) for the extracted complex formed between the ligand and UO₂²⁺.

A novel coumarin-pillar[5]arene derivative (P5C10) was prepared. Fluorescence spectroscopy indicates that P5C10 shows good selectivity towards methyl-parathion. A combination of NMR spectra, MALDI-TOF spectra and computational calculations reveals the formation of a host-guest complex driven by π-π stacking interactions.

Pillar[5]arene has been selectively oxidized to pillar[n]arene[5−n]quinones in relatively high yields and short reaction time.

A series of novel copillar[5]arenes 1a–1f containing different substituents were synthesized. Their complexation indicated that the modified substituted group of copillar[5]arene and the symmetry of guest played an important role in the complexation model and selectivity.