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 ( 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.