Anomalous Halogen–Halogen Interaction Assists Radial Chromophoric Assembly

Abstract

The design of highly efficient supramolecular architectures that mimic competent natural systems requires a comprehensive knowledge of noncovalent interactions. Halogen bonding is an excellent noncovalent interaction that forms halogen-halogen (X2) as well as trihalogen interacting synthons. Herein, we report the first observation of a symmetric radial assembly of chromophores ( R3̅ c space group) composed of a stable hexabromine interacting synthon (Br6) that further push the limits of our understanding on the nature, role, and potential of noncovalent halogen bonding. Contrary to the destabilization proposed for Type-I X2 interactions, Br6-synthon-possessing Type-I X2 interactions exhibit a stabilizing nature owing to the exchange-correlation component. The radial assembly of chromophores is further strengthened by intermolecular through-space charge transfer interaction. Br6-synthon-driven 3-fold symmetric radial assembly render a lattice structure that reminisces the chromophoric arrangement in the light harvesting system 2 of purple bacteria.