Supramolecular Helical Columnar Structures Formed by Hydrogen-Bonded Disk-Like (Phenylethynyl)benzene Derivatives with L-Alanine Pendant Groups: Helix Stability and Supramolecular Helical Sense Inversion

摘要

To investigate the influence of the number of substituents on supramolecular assemblies of hydrogen-bonded disk-like (phenylethynyl)benzene derivatives with chiral L-alanine dodecyl groups, a tris(phenylethynyl)benzene derivative 3 and a tetrakis(phenylethynyl)benzene derivative 4 were synthesized. The behavior of these supramolecular assemblies was compared with that of the previously reported hexakis(phenylethynyl)benzene derivative 6. It is clearly shown that the stability of the supramolecular helical columnar structure is enhanced by increasing the number of substituents, namely the number of amide groups contributing to the hydrogen bonding. In addition, along with 6, 4 also exhibits a solvent-induced supramolecular helical sense inversion. Furthermore, 4 exhibits a thermally reversible supramolecular helical sense inversion at a critical solvent composition.