Biossíntese de CuO/Cu2O usando extrato aquoso de Curcuma longa L. para aplicação em reações de cicloadição [3+2] entre azidas e alquinos

Abstract

The development of new materials through nanotechnology has gained increasing attention due to their broad applicability, especially metallic nanoparticles and metal oxides such as copper and copper oxides. Conventional synthesis methods are gradually being replaced by green approaches, aiming to reduce the use of toxic reagents and expensive, less sustainable equipment. These eco-friendly methods utilize natural sources such as microorganisms, algae, and plant extracts. Curcuma longa L., for instance, is a plant well known for its anti-inflammatory, antimicrobial, and antioxidant properties. In this context, the present study aims to synthesize copper oxide nanoparticles (CuO/Cu₂O) using an aqueous extract of Curcuma longa L. and anhydrous copper sulfate as the precursor, characterize them using UV-Vis, FTIR, XRD, SEM, TEM and EDX techniques, and evaluate their catalytic potential. The synthesis was carried out by adding the plant extract to a 100 mM precursor solution, followed by centrifugation and drying of the resulting material. The obtained nanoparticles were calcined to investigate their morphological structure and purity. An optimization study was also conducted using the nanoparticles as a catalyst in multicomponent click chemistry reactions. Nanoparticle formation was confirmed through solution color changes, optical features in the UV-Vis spectrum, and the presence of reducing functional groups identified via FTIR. XRD patterns exhibited diffraction peaks corresponding to CuO and Cu₂O, with average crystallite sizes of 15.88 nm and 16.71 nm, respectively. TEM images revealed nearly spherical structures presenting an average particle diameter of 8 nm. The synthesis proceeded with the optimization of the reaction conditions, employing 1 mg of catalyst and achieving yields of up to 96%. These results demonstrate the successful development of a material synthesized via a green route, with promising catalytic efficiency for click chemistry reactions. In this way, this work contributes to the advancement of sustainable methodologies for the production of new materials and their application in organic synthesis.