Synthesis of Gold Nanoparticles Capped-Benzoic Acid Derivative Compounds (o-, m-, and p-Hydroxybenzoic Acid)

Agustina Sus Andreani (Department of Chemistry, Faculty of Mathematics and Natural Sciences, Universitas Gadjah Mada, Sekip Utara Yogyakarta 55281, Indonesia)
Eko Sri Kunarti (Department of Chemistry, Faculty of Mathematics and Natural Sciences, Universitas Gadjah Mada, Sekip Utara Yogyakarta 55281, Indonesia)
Sri Juari Santosa (Department of Chemistry, Faculty of Mathematics and Natural Sciences, Universitas Gadjah Mada, Sekip Utara Yogyakarta 55281, Indonesia)

Indonesian Journal of Chemistry
Vol 19, No 2 (2019)

The effect of a hydroxyl functional group of the benzoic acid derivative compound, i.e. o-hydroxybenzoic acid, m-hydroxybenzoic acid, and p-hydroxybenzoic acid on the synthesis of AuNPs has been studied. It was revealed that the pH, heating time, the concentration of capping agent and the concentration of Au3+ affected the formation of AuNPs. We discovered that o-hydroxybenzoic acid possessed the highest stability, yet it needed the highest concentration of Au3+ and faster reaction time than p-hydroxybenzoic acid and slower than m-hydroxybenzoic acid. The stability was verified by means of UV-Vis spectrophotometer, XRD, TEM, Particle Size Analyzer (PSA), and Zeta Potential with an aging time of more than 5 months. We concluded that o-hydroxybenzoic acid acquired the most effective redox reaction instead of m-hydroxybenzoic acid and p-hydroxybenzoic acid, resulted in the smaller sized and unaggregated AuNPs. We also confirmed that the hydroxyl group of o-hydroxybenzoic acid, m-hydroxybenzoic acid and p-hydroxybenzoic acid is the functional group responsible for the reduction of Au3+ to Au0.