Self-inclusion of a new calix[4]arene derivative via associated acetonitrile: X-ray diffraction and density functional theory studies

A new calix[4]arene derivative, 11,23-bis(hydroxyiminomethyl)-25,27-dihydroxy-26,28-di-n-propoxycalix[4]-arene (B), was synthesized and a compound, with composition of B center dot 2CH(3)CN, was fully characterized. H-1 NMR showed that B in the B center dot 2CH(3)CN adopts a cone conformation. X-ray diffraction analysis confirmed the conformation found in solution. In the crystal network, self-inclusion phenomenon is present in a dimeric unit of B center dot 2CH(3)CN via embedding each other. The noncovalent interaction energies were calculated at B3LYP/6-311G(d) level and corrected by basis set superposition error (BSSE). In half a dimeric unit, one CH3CN is stabilized via hydrogen bonding formed between nitrogen atom of the acetonitrile and one hydroxyimino group, with bonding energy of -5.02 kJ center dot mol(-1), and the other one stabilized by hydrogen bonding formed between nitrogen atom of the acetonitrile and the other hydroxyimino group, with bonding energy of -14.23 kJ center dot mol(-1), and by inclusion to hydrophobic cavity of the other half of the dimeric unit via C-H center dot center dot center dot pi interaction, with bonding energy of -3.77 kJ center dot mol(-1), doubling of which is a driving force for embedding two B center dot 2CH(3)CN together.