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

Abstract

In this work we have applied a double isosteric substitution of the amide groups presented in the gelator N,N′-((1S,2S)-cyclohexane-1,2-diyl)didodecanamide (C₁₂-Cyc) by 1,2,3-triazole rings affording the corresponding isosteric gelator (click-C₁₂-Cyc). This approach enabled the preparation of different metallogels and fine-tuning their properties. In particular, C₁₂-Cyc was found to form stable and reversible metallogels with Pd^II and Au^III in DMSO and DMF, whereas click-C₁₂-Cyc formed metallogels in these solvents only in the presence of Au^III. Comparing the gels made of C₁₂-Cycvs.click-C₁₂-Cyc in the presence of HAuCl₄·3H₂O, the former showed higher T_gel values and 5–8 times slower gelation kinetics. Furthermore, the incorporation of Et₃N as reducing agent in the formulations facilitated the in situ formation of non-aggregated gold nanoparticles embedded in the viscoelastic networks made of either pure isosteres or with an equimolar mixture of click-C₁₂-Cyc and C₁₂-Cyc. So-formed NPs showed similar size distribution regardless the gold concentration and the nature of the gelator system.