Eco-friendly production of palladium-modified γ-cyclodextrin and its methyl cinnamate inclusion complex: Catalyst for reduction and antibacterial properties

Abstract

Addressing the conversion of toxic substances into non-toxic was a significant challenge in our environmentally compromised world. This manuscript focuses on elucidating the synthesis, chemical composition, and structure of a cinnamic acid (CA) derivative named methyl cinnamate (MC) using analytical techniques such as 1H NMR and FT-IR spectroscopy. Furthermore, we implemented an adapted synthetic procedure to effectively produce a modified version of γ-cyclodextrin known as palladium (Pd)-modified γ-CD (Pd-γ-CD). The Pd metal particles were uniformly distributed throughout the structure. The resulting product underwent characterization through a range of techniques, encompassing XRD, SEM, FT-IR, EDAX, TGA, and UV–visible spectroscopy. The UV–visible spectroscopy results confirmed the formation of a 1:1 inclusion complex between MC and both native γ-CD and Pd-γ-CD. Using the Benesi-Hildebrand equation and the Gibbs free energy relation, we calculated the binding constant and free energy change for the complex formation, respectively. The molecular interaction between Pd-γ-CD and MC was elucidated by 1H NMR and 2D NMR (ROESY) spectroscopy. Additionally, we investigated the catalytic reduction properties of our novel complexes, as well as native γ-CD and Pd-γ-CD, against 2,4-dinitrophenol. Notably, the Pd-γ-CD complex exhibited exceptional catalytic reduction performance. Moreover, we also evaluated the antibacterial effects of γ-CD, Pd-γ-CD, and their complexes against S. aureus and E. coli. The results indicated that the Pd-γ-CD complex showed superior efficacy against S. aureus bacteria compared to the other samples.