A series of FFK tripeptides capped with phenylacetic acid of various fluoro-substitutions at N-terminus have been synthesized and examined for the self-assembly in aqueous conditions. The material property of FFK tripeptides dramatically changes from precipitate to hydrogel phase upon increasing the number of fluorine atoms. Peptides linked with benzyl (B-FFK) or monofluoro-benzyl (MFB-FFK) groups rapidly form solid precipitates at physiological pH conditions. Trifluoro-decorated compound (TFB-FFK) self-assembled into a metastable hydrogel which slowly transformed into a solid precipitate upon standing. A stable hydrogel formation was noticed as in the case of pentafluorobenzyl-diphenylalanyllysine (PFB-FFK) compound. TEM analysis indicates that PFB-FFK peptide assembled into twisted nanofibril structures which is predominantly stabilized by strong quadrupole π-stacking interactions and electrostatic interactions of amino acid side chain. Further, the combination of PFB-FFK and PFB-FFD peptides were also investigated for hydrogelation and the self-assembly of such systems resulted in the formation of untwisted 1D nanofibrils structures. The supramolecular coassembled hydrogels of variable stiffness have also been achieved by modulating the concentration of the peptide components which was evident from the rheological analysis. Such low molecular weight (LMW) peptides materials with tuneable mechanical properties might be a potential material for a wide range of applications in nanotechnology and biotechnology.