Macrocycle-based fluorochromic systems

Macrocyclic compounds have shown great potential in constructing tunable fluorochromic systems and functional supramolecular materials owing to their unique structural merits, facile functionalization, and diverse applications. In this perspective, we summarize recent progress in macrocycle-based fluorochromic systems and their applications in smart materials, which are classified by the types of macrocycles. Classical macrocycles, including cyclodextrins, cucurbiturils, calixarenes, and pillararenes, have shown guest binding-, vapor-, mechano-, and charge-transfer-induced fluorescence-switching behaviors. Emerging macrocycles, such as tetraphenylethylene-based, dicyano-based, and polycyclic aromatic hydrocarbon-based macrocycles, exhibit wide-range tunability of emission colors and multi-stimuli-responsive fluorescence modulation. Furthermore, innovations in scaffolds and mechanisms in supramolecular functional systems will unlock new horizons in smart material engineering. Finally, a brief outlook on this promising area of research is outlined. This perspective aims to provide timely insight into a burgeoning area of supramolecular chemistry and fluorochromic materials.