From the decks to the bridges: Optoelectronics in [2.2]paracyclophane chemistry

In this microreview, we highlight optical properties of [2.2]paracyclophanes (pCps). We demonstrate how the spectroscopic properties that stem from the strained and π-stacked structure have resulted in pCps being incorporated in materials science and polymer synthesis. As a result of chromophore substitution, internal charge transfer (ICT) between the two rings of the cyclophane core produce frameworks with unique optical properties. Deck-substituted molecules and polymers have beensynthesized that possess donor and acceptor groups that affect internal charge transfer (ICT). We also demonstrate that bridge-substituted [2.2]paracylophanes, although not well studied in this context, display unexpected optical properties owing to nonconventional ICT. A highlight is a recent templated solid-state synthesis that affords a pCp that exhibits dramatic red-shifted fluorescence. Architectures based on [2.2]paracyclophane (pCp) have received considerable attention owing to distinct spectroscopic properties. The properties stem from internal charge transfer (ICT) between the rings of the cyclophane core. The aim of this microreview is to highlight deck- and bridge-substituted pCps and describe how the optical properties of pCp can be perturbed to affect electronic communication.