5-(1H-1,2,3-Triazol-5-yl)isophthalic Acid: A Versatile Ligand for the Synthesis of New Supramolecular Metallogels

Sulfonamide as amide isostere for fine-tuning the gelation properties of physical gels

(S)-2-Stearamidopentanedioic acid (C18-Glu) is a known LMW gelator that forms supramolecular gels in a variety of solvents. In this work, we have carried out the isosteric substitution of the amide group by a sulfonamide moiety yielding the new isosteric gelator (S)-2-(octadecylsulfonamido)pentanedioic acid (Sulfo-Glu). The gelation ability and the key properties of the corresponding gels were compared in terms of gelation concentration, gel-to-sol transition temperature, mechanical properties, morphology, and gelation kinetics in several organic solvents and water. This comparison was also extended to (S)-2-(4-hexadecyl-1H-1,2,3-triazol-4-yl)pentanedioic acid (Click-Glu), which also constitutes an isostere of C18-Glu. The stabilizing interactions were explored through computational calculations. In general, Sulfo-Glu enabled the formation of non-toxic gels at lower concentrations, faster, and with higher thermal-mechanical stabilities than those obtained with the other isosteres in most solvents. Furthermore, the amide-sulfonamide isosteric substitution also influenced the morphology of the gel networks as well as the release rate of an embedded antibiotic (vancomycin) leading to antibacterial activity in vitro against Staphylococcus aureus.

Expanding the limits of amide-triazole isosteric substitution in bisamide-based physical gels

Gelation of organic solvents using N,N'-((1S,2S)-cyclohexane-1,2-diyl)didodecanamide (C12-Cyc) is driven by its self-assembly via antiparallel hydrogen bonds and van der Waals intermolecular interactions. In this work we carried out a dual isosteric substitution of the two amide groups with 1,2,3-triazole rings affording the corresponding isosteric gelator (click-C12-Cyc). A detailed comparative study in terms of the gelation ability and gel properties demonstrated that the 1,2,3-triazoles can take over all of the functions derived from the amide groups offering a versatile strategy for tuning the properties of the corresponding gels. This is not an obvious outcome because the directional amide groups in C12-Cyc constitute the source of the hydrogen bonds to build the 3D self-assembled network. Furthermore, theoretical calculations revealed that click-C12-Cyc can adopt a wide variety of interacting patterns, whose relative stability depends on the polarity of the environment, this is in good agreement with the experimental data obtained regarding its gelation ability. Other important features of click-C12-Cyc for potential practical applications are its non-cytotoxic character and its phase-selective gelation of water-oil mixtures.

Use of a bis-1,2,3-triazole gelator for the preparation of supramolecular metallogels and stabilization of gold nanoparticles

In this work, a series of functional metallogels have been prepared using a bis-1,2,3-triazole gelator prepared using the isosteric substitution method.