Noncovalent Interactions between Stacked Arenes in 1,8-Bis-(1-naphthyl)-naphthalenes

A number of 1,8-bis(1-naphthyl)-naphthalenes, bearing different substituents in the 1-naphthyl moieties have been prepared to investigate the noncovalent interactions between the stacked arenes. The best geometries were determined by means of DFT calculations, and experimentally checked by NMR and electronic circular dichroism (ECD). High temperature NMR spectroscopy allowed for the determination of the balance between dispersive and electrostatic contributions (ratio between two diastereomeric syn/anti isomers of compounds 1-6), while ECD analysis of the syn isomers of compounds 3-5 allowed for a deeper insight on the electrostatic contributions that drive the geometry between the interacting rings. The two rings preferentially adopt a parallel displaced geometry, whose interaction energy is strongly influenced by the electrostatic features of the two naphthyl rings, and that dispersive forces play a very minor role.