DFT Study of the ExBox·Aromatic Hydrocarbon Host–Guest Complex

The structures of ExBox(4+) 1 and its host-guest complexes with the linear acenes benzene, naphthalene, anthracene, and tetracene were optimized using DFT (ωB97X-D/6-311G(d,p)) in both the gas and solution phases. The structure of 1 systematically varies as it moves from the gas to solution to the solid phase: the outward bending of the triaryl fragment diminishes in this series. The structures of the complexes with anthracene and tetracene are in very good agreement with their X-ray structures. The gas phase binding energy is linearly related to the size of the acene, with the binding free energy of all complexes predicted to be exoergonic in both gas and solution phases.