Calixarenes are a class of macrocyclic compounds with a bowl-shaped structure with multiple aromatic rings. These compounds can serve as supramolecular host materials, capable of binding and transporting guest molecules through their cavities. The size and shape of the calixarene cavity can be tuned by chemical modifications, making them versatile in different applications. Calixarenes are often used in the separation and purification of chiral compounds, as well as in the design of drug delivery systems. They can also be used as sensors and biosensors due to their ability to bind specific analytes with high selectivity and sensitivity.