Dimeric Calix[4]arenes, Synthesis and their Application: A Review

Abstract

Calix[n]arene is an attractive host for molecular recognition due to its accessibility through the hollow cavity and shallow bowl shape and has been used as a receptor over the last 30 years. Calix[n]arene has a small cavity, so designing a flexible molecule to recognize nano to large biomolecules is a challenging goal in host-guest chemistry. Dimeric calix[n]arene is formed by linking two calix[n]arene sub-units to each other. Their considerable structural features and relative diversity of modifying the upper or lower rim represent outstanding and greatly adaptive structures for designing bulky and complex building blocks adequate for selfassembly and molecular recognition. Their ability to form supramolecular structures for a wide range of applications, including the recognition of nano-molecules and large biological molecules, has been extensively studied. This review details the progress of the host-guest chemistry of dimeric calix[n]arenes, emphasizing the synthetic pathways employed for their production and their self-assembly properties. Dimerization of calix[n]arene occurs in two ways (1-through non-covalent bonding such as H-bonding or self-assembly, and 2-through covalent bond formation such as amide bond formation, multi-component reactions and Sonogashira cross-coupling reaction and metathesis reactions). In this work, we focused on dimerization through covalent bond formation, due to having more applications and diverse synthetic applications.