By systematically altering the number and position of phenylalanine and
carboxylate groups on a series of hydrogelators containing a naphthalene
motif, we evaluated the correlation of molecular structures, self-assembly,
and the rheological properties of the hydrogels. The storage moduli of the
hydrogels decrease with the increase of the number of phenylalanine or with
the insertion of a cysteine residue, and the effect of the carboxylic group
on the rheological properties depends on the backbone of the hydrogelators.
Transmission electron microscopy shows that these hydrogelators
self-assemble in water to form nanofibers and result in threedimensional
networks. Circular dichroism experiment indicates the hydrogelators
self-assemble to form β-sheet-like structure within the nanofibers. This
work suggests that control of the synergy of hydrogen bonding and
aromatic-aromatic interactions may offer a feasible way to modulate the
rheological properties of molecular hydrogels consisting of small
molecules.