Stabilized Copper(I) Oxide Nanoparticles Catalyze Azide‐Alkyne Click Reactions in Water

A novel form of polyvinylpyrrolidone (PVP) coated copper(I) oxide nanoparticle (Cu2O‐NP) was prepared and used to catalyze azide‐alkyne click reactions in water under aerobic conditions. The nanoparticles were well dispersed in aqueous solutions and have a size of 20±10 nm, as determined by transmission electron microscope (TEM). Inductively coupled plasma (ICP), X‐ray powder diffraction (XRD), and X‐ray photoelectron spectroscopy (XPS) analyses demonstrated that the main content of Cu2O‐NP is copper(I). The cytotoxicity of it was evaluated by an in vitro 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide (MTT) assay and its catalytic efficiency for azide‐alkyne click reactions was studied in water and organic solvents at physiological temperatures. Our results indicate that Cu2O‐NP is more efficient in catalytic reactions in water for both aliphatic and aromatic azides and alkynes and less toxic than the commonly used CuSO4/reductant catalyst systems.