Syntheses, Reactivity, and Structures of Cyclotrimeric Ring Systems with Magic Display of Three-Fold Symmetry

Benzocyclotrimers (BCTs) have attracted growing interest due to their potential for building host molecules that act as tweezers, baskets, cages, bowls, and others that allow incoming molecular species to enter into their cavities forming a variety of host-guest complexes for fascinating applications. Moreover, BCTs have been greatly exploited as key precursors for developing curved molecular geometries toward accessing architecturally unique and technologically useful compounds. They also possess interesting applications in molecular and chiral molecular recognition as well as in the construction of higher symmetric polyhedra. Further, BCTs have been recognized as models for study of Mills-Nixon effect. They have also been useful in the synthesis of stabilized cationic derivatives and p-arene complexes. Fluorescence enhancement via charge-transfer effect has also been reported for donor-acceptor substituted BCTs. Highly stable pure blue emission has also been achieved for OLED technological applications for some BCTs. Similarly, they have also proved to be valuable precursors for advanced display technologies. There is a great demand for developing straightforward synthetic protocols toward such skeleta using readily available starting material. This review encompasses various stages of development in their synthesis, reactivity, and useful molecular architectures derived from them.