Recent progress using novel tetraphenylethylene-based macrocyclic hosts in water

Macrocyclic structures are popular in supramolecular chemistry and have enjoyed considerable success as platforms for elaboration to container compounds and new materials. Host/guest studies in organic media have relied heavily on structures derived from crown ethers, calixarenes, cucurbiturils, resorcinarenes and pillararenes over the past decades. More recently, their water-soluble versions have been developed for potential applications in biology. Inspired by nature and the need for large-sized containers, Cao and co-workers have designed and synthesized a series of novel macrocyclic hosts based on the tetraphenylethylene (TPE) platform. These compounds have cationic frameworks with well-defined hydrophobic cavities for recognition of biomolecules (e.g. amino acids, nucleosides, peptides, proteins, coenzyme factors) in water. They offer multiple adaptive responses as sensors through fluorescence, circular dichroism and circularly polarized luminescence. These TPE-based hosts also show promising applications as stimuli-responsive fluorescent materials, in drug delivery and as artificial photofunctional systems. Herein, this review highlights this work as it establishes a new class of biomimetic, water-soluble supramolecular macrocyclic hosts.