In situ formation of AuNPs using fatty N-acylamino hydrazide organogelators as templates

This work reports, for the first time, the synthesis of new fatty N-acylamino hydrazides and demonstrates the activity of these compounds as low-molecular-weight organic gelators and templates for preparation of gold nanoparticles (AuNPs). Initially, we evaluated the gelation properties of fatty N-acylamino hydrazides in various nonpolar and polar solvents (n-hexane, toluene, benzene, cyclohexane, and ethanol). Fatty N-acylamino hydrazide derived of the glycine and stearic acid (C18:0) did not form gels in any of the tested solvents. All other hydrazides did form gels in at least two of the organic solvents tested. The morphology of each gel was observed via scanning electron microscopy. The organogels derived from alanine, valine, and phenylalanine had translucid properties, while the serine organogels were opaque. Afterwards, the synthesis of AuNPs in the presence of the organogelator using microwave irradiation was realized. Organogelator agents reduced HAuCl4 showing plasmon band peaks between 530 and 543 nm. In addition, the method does not require a reducing agent, which is typically a potential source of contamination and toxicity. Therefore, this work confirms the importance of the hydrazide group of the new fatty N-acylamino hydrazides in gel formation and as organogelator agents for preparation of AuNPs.