Highly efficient complexation of sanguinarine alkaloid by carboxylatopillar[6]arene: pKa shift, increased solubility and enhanced antibacterial activity.

Encapsulation of a physiologically active substance, sanguinarine (SA), by a water soluble carboxylatopillar[6]arene (CP6A), is described. The efficient complexation by CP6A, giving a Ka value of (2.4 ± 0.3) × 105 M-1 in pH 7.4, served to increase the water solubility by 4.3-fold, cause a 2.02 shift in pKa, and enhance the antibacterial activity of SA.

Efficient complexation between pillar[5]arenes and neutral guests: from host-guest chemistry to functional materials.

Since their discovery in 2008, pillar[n]arenes have been a popular family of macrocyclic arene hosts due to their accessible one-step synthesis, convenient functionalization, symmetrical prism structures and perfect cavity host-guest properties. Compared with other macrocyclic hosts, the most peculiar recognition behavior of pillararenes is the strong binding affinities of pillar[5]arenes (P5As) towards neutral guests in organic media, which is unfeasible for classic crown ethers and calixarenes. The intriguing properties have found extensive applications in many fields from supramolecular chemistry to materials science. This feature article provides a detailed summary of the molecular recognition of P5As and neutral guests, where the driving forces, binding mechanisms, and binding selectivities are comprehensively discussed. Furthermore, brief highlights of research progress in the functional applications based on the neutral guest⊂P5A motifs were also discussed, including the construction of complex topological superstructures (e.g. rotaxanes, catenanes and daisy chains), supramolecular polymers, and functional materials.