Low-molecular weight gelators (supramolecular,
or simply molecular
gels) are highly important molecular frameworks because of their potential
application in drug delivery, catalysis, pollutant removal, sensing
materials, and so forth. Herein, a small dipeptide composed of N-(tert-butoxycarbonyl)pentafluoro-l-phenylalanine and O-benzyl-l-tyrosine methyl ester
was synthesized, and its gelation ability was investigated in different
solvent systems. It was found that the dipeptide was unable to form
gel with a single solvent, but a mixture of solvent systems was found
to be suitable for the gelation of this dipeptide. Interestingly,
water was found to be essential for gelation with the polar protic
solvent, and long-chain hydrocarbon units such as, petroleum ether,
kerosene, and diesel, were important for gelation with aromatic solvents.
The structural insights of these gels were characterized by field-emission
scanning electronic microscopy, atomic force microscopy, Fourier transform
infrared analysis, and X-ray diffraction studies, and their mechanical
strengths were characterized by rheological experiments. Both of the
gels obtained from these two solvent systems were thermoreversible
in nature, and these translucent gels had potential application for
the treatment of waste water. The gel obtained from dipeptides with
methanol–water was used to remove toxic dyes (crystal violet,
Eriochrome Black T, and rhodamine B) from water. Furthermore, the gel obtained from dipeptide with assistance from toluene–petroleum
ether was used as a phase-selective gelator for oil-spill recovery.