Tunable solvent-induced gelation of dipeptide-based gelators: exploring the role of solvent and acid concentration

The tunability of the solvent-induced gelation mechanism using tert-butyl (tBu) containing solvents and two tBu-protected dipeptide precursor gelators (Boc-Phe-Phe-OtBu - 1 and Boc-Leu-Phe-OtBu - 2) is reported. Gelation behaviour, network morphology, material stability, and gelators' structures can be adjusted by both the solvent type and acid concentration. While tert-butyl chloroacetate (tBuClOAc) enables rapid gelation, tert-butyl methyl ether (tBuOMe), acting as a solvent with two leaving groups, promotes the in situ formation of two different gelators and prolongs the gelation time. Gel-to-sol transition temperature (T_gel-sol), NMR, HR-MS, ATR-FTIR and TEM analyses revealed that both the solvent type and acid concentration influenced the precursor gelator-to-gelator conversion efficiency, as well as the secondary structure (β-sheet and helical-like motif) and morphology of the resulting gels. This study highlights the adaptability of solvent-induced gelation across different solvent environments. In addition, the findings demonstrate that the solvent type and acid loading are powerful tools for tuning the properties of peptide-based supramolecular organogels with potential applications in biomedical and materials science.