Supramolecular structures and crystal stability of diisobutylaminomethylated calix[4]resorcinarenes

Three diisobutylaminomethylated calix[4]resorcinarenes 4–6 were synthesized by the condensation reaction of resorcinarenes 1–3 with diisobutylamine and an excess of formaldehyde. The crystals and supramolecular structures of compounds 4–6 were determined by single crystal X-ray diffraction along with proton nuclear magnetic resonance spectroscopy. The resorcinarene molecules occur in the crystal in the bowl-like form, are stabilized by a collar of exquisite intramolecular hydrogen bonding networks which all proceed in the same direction around the upper rim of the macrocycle. Four amino groups involved in intramolecular hydrogen bonding enlarge the intramolecular cavity of the resorcinarene, which form an encapsulating with “lid” over an included CH2Cl2 guest molecule. Adjacent molecules of compounds 4–6 connect through intermolecular hydrogen bonds, which rotated and localized to a staggered orientation in order to minimize the steric repulsion between them. Dichloromethane acts as the guest molecule for the self-assembly of diisobutyaminomethylated calix[4]resorcinarenes supramolecular structures.