DMSO solvates of tert-butylcalix[6]arene and related multisolvent structures

tert-Butylcalix[6]arene (TBC6) exhibits a rich crystal energy landscape, with structural diversity driven by macrocycle conformation, guest inclusion and self-assembly. Using multicomponent crystallization mixtures containing DMSO and additional solvents (e.g. DMF, chlorobenzene, 1,2-dichlorobenzene, anisole, THF), we obtained seven new TBC6 solvates. One structure, crystallized in the presence of pyridine, adopts a winged-cone conformation with a bilayer arrangement in the crystal. The remaining six are isostructural and feature a columnar packing of TBC6 in a 1,2,3-alternate conformation stabilized by four strong interactions with DMSO: two hydrogen bonds and two C-H...π interactions. Notably, DMSO in the TBC6 cavity is released at elevated temperatures (∼200°C), consistent with its stronger binding energy as calculated using DFT methods. TBC6-TBC6 interactions, both within and between columns, dominate the crystal packing, with intracolumnar contacts contributing twice as much stabilization as intercolumnar ones, where additional solvent guests are located. Hirshfeld surface analysis supports these findings, highlighting extensive contact areas between TBC6 molecules. This study contributes to understanding how solvent properties, interaction energies, and packing preferences drive the solid-state organization of calixarenes-molecules with broad applications in separation, recognition, and supramolecular chemistry.