The C-Cl center dot center dot center dot pi interactions inside supramolecular nanotubes of hexaethynylhexamethoxy[6]pericyclyne

Model complexes of hexaethynylhexamethoxy[6] pericyclyne (HM6P) molecules, with or without dichloromethane (DCM) guests, have been calculated at the M05-2X/6-311G(d,p) DFT level. Analysis of nonbonding interactions shows that the cohesion of the supramolecular tubular assemblies previously observed in the crystal state, relies mainly on C-H center dot center dot center dot O hydrogen bonds between axial ethynyl and equatorial methoxy substituents of stacked HM6P C-18 macrocycles in a cyclohexane-like chair conformation. The intrinsic binding energy of one HM6P molecule with two neighbors is calculated to be more than 40 kcal mol(-1). The inner channel of the stacks (of ca. 8 angstrom diameter) are suitable for hosting DCM molecules. Using the Atoms In Molecules (AIM) theory, the interaction between DCM molecules and surrounding triple bonds is analyzed in terms of sigma-hole-directed C-Cl center dot center dot center dot pi halogen bonds. A s-hole-directed Cl center dot center dot center dot Cl interaction between two chlorine atoms of different DCM molecules is also evidenced.