The importance of interactions between methyl groups and aromatic rings in homo and hetero-cyclophane structures. A molecular mechanics and X-ray crystallographic investigation

Abstract

A series of macrocycles (L¹, L², L³, L⁴) generated by the [2+3] Schiff base condensation of tris-2-aminoethylamine with a series of aromatic aldehydes have been investigated. The crystal structure of [L³], CHCl₃, 2H₂O is reported here to complete the set of structural data for these macrocycles. In all four structures, the three aromatic rings adopt a triangular disposition around the long ellipsoidal diameter, the N_br-N_br axis. In these structures, attractive H…π interactions predominate and the conformations are rationalised by molecular mechanics calculations which show the importance of these interactions.