Supramolecular Polymorphism of the Hydrogen-Bonded -Symmetrical Hexadehydrotribenzo[12]annulene Derivative.

The -symmetric hexadehydrotribenzo[12]annulene () derivative () with three tetradecylamide (-NHCOCH) chains capable of hydrogen-bonding interaction formed either a two-dimensional lamellar () or a one-dimensional (1D) nanofiber () molecular assembly, depending on the association state of the amide hydrogen bonds in the solution phase. The intermolecular amide hydrogen-bonding modes in the and structures were different from each other. The structure was metastable, 2.2 kJ mol less stable than that of the structure, and was obtained through organogel formation. In CHCl, exhibited a 1D association behavior following the isodesmic model ( = 2.18 × 10 M) due to intermolecular amide hydrogen bonds, whereas the presence of CHCN inhibited this association state. The structure had larger amplitude dynamics about the polar amide group than that of the structure, undergoing a phase transition from the to the structure upon heating. The absorption spectra of and solid-state were different from each other, exhibiting different optical properties. The coexistence of intermolecular amide hydrogen bonds and van der Waals interactions among the -symmetric molecules resulted in polymorphic phenomena, where energetically similar molecular assemblies were expressed.