An o-carborane-based naphthalene macrocyclic arene: dual-state emission and C60 recognition

Abstract

An o-carborane-based naphthalene macrocyclic arene was designed and synthesized via a Friedel–Crafts alkylation strategy. The macrocycle was fully characterized by spectroscopic methods and single-crystal X-ray diffraction. Owing to the rigid π-conjugated naphthalene framework and the three-dimensional steric effect of the o-carborane unit, the macrocycle exhibits intrinsic dual-state emission behaviour. It shows solvent-dependent fluorescence in solution and efficient emission in the solid state, together with an aggregation-induced emission (AIE) characteristic. Photophysical studies and theoretical calculations indicate that the emission properties are governed by an intramolecular charge transfer (ICT) process and sterically regulated aggregation. In addition, the macrocyclic arene displays a pronounced fluorescence quenching response toward C₆₀ in toluene. This work provides a viable strategy for constructing luminescent macrocyclic systems with dual-state emission and fullerene-responsive behaviour.