Weak intermolecular interaction directed assembly of calix[4]arene derivatives

Abstract

Crystals of cone-di-formyl-calix[4]arene (16), 1,3-alt-di-O-benzoyl-di-formyl-calix[4]arene (17), 1,3-alt-tetra-O-n-propyl-tetra-formyl-calix[4]arene (18), 1,3-alt-tetra-O-i-propyl-di-formyl-calix[4]arene (19), 1,3-alt-tetra-O-i-propyl-tri-formyl-calix[4]arene (20), 1,3-alt-tetra-O-i-propyl-tetra-cyano-calix[4]arene (21), and pc-A,B-di-O-i-propyl-tetra-formyl-calix[4]arene·1/2CH₂Cl₂ (22·1/2CH₂Cl₂) obtained in crystallisation solvent chloroform–hexane have been studied. These crystals form different architectures through some weak intermolecular forces, such as C–H⋯O, C–H⋯π, O⋯π and π⋯π interactions. Compounds 16–18 form classic ‘head-to-head’ dimer or ‘head-to-tail’ dimer motifs by C-H⋯O interactions, while compound 22 forms an ‘up-down’ dimer structure via C–H⋯π interactions. Compounds 19–21 adopting a 1,3-alt conformation are closely packed together by weak intermolecular interactions. The results indicate that weak intermolecular interactions can determine the assembly pathways of calix[4]arene derivatives.