Recent Applications of Pillar[n]arene-Based Host-Guest Recognition in Chemosensing and Imaging

Pillar[n]arene is a novel kind of synthetic supramolecular macrocyclic host characterized by its particular pillar-shaped structure consisting of an electron-rich cavity and two finely adjustable rims. Benefiting from its rigid structure, facile synthesis, ease of functionalization, and outstanding host-guest chemistry, pillar[n]arene shows great potential for diverse applications. Significantly, the host-guest recognition of pillar[n]arene provides a novel approach for chemosensing and imaging. Herein, this Review critically and comprehensively reviews the applications of pillar[n]arene-based host-guest recognition in chemosensing and imaging. The sensing and imaging mechanisms as well as the unique roles and advantages of pillar[n]arene-based host-guest recognition are summarized. In addition, preparations of hybrid materials based on pillar[n]arene and inorganic materials are also introduced comprehensively in the light of chemosensing and imaging. Finally, current challenges and perspectives on pillar[n]arene-based host-guest recognition in chemosensing and imaging are outlined.

A fluorescent "ON-OFF-ON" switch for the selective and sequential detection of Hg2+ and I- with applications in imaging using human AGS gastric cancer cells

A new fluorescent "on-off-on" probe (BIPQ) is designed and developed which selectively binds with Hg²⁺; its emission intensity is quenched almost 40-fold at 455 nm without interference from other metal cations. On gradual addition of I^- to the solution of BIPQ-Hg²⁺, the emission reverts to its original intensity. The limits of detection of BIPQ for Hg²⁺ and I^- are found to be on the order of 3.12 × 10^-9 and 5.48 × 10^-8 M, respectively, which shows clearly that BIPQ can sense Hg²⁺ at a very minute level. DFT and TDDFT studies are conducted with the probe to establish similarity between theoretical and experimental outcomes. Finally, to demonstrate its practical benefit in biological fields, live cell imaging experiments with BIPQ are carried out to detect Hg²⁺ in human AGS gastric cancer cell lines.

Pillararene-based fluorescent chemosensors: recent advances and perspectives

This feature article summarizes recent research in the pillararene-based fluorescent chemosensor field in terms of ion sensing, small molecule recognition, biomolecule detection, fluorescent supramolecular aggregates, and biomedical imaging.