Practical Coprecipitation Approach for High-Aspect Ratio Cupric Oxide Nanoparticles: A Sustainable Catalytic Platform for Huisgen and Fluorogenic Click Chemistry

Herein, we disclose a practical coprecipitation method, which grants access to cupric oxide nanoparticles in high aspect ratio together with comprehensive characterization (X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HR-TEM), dynamic light scattering (DLS), Brunauer-Emmett-Teller (BET), diffuse reflectance spectroscopy (DRS), Fourier transform infrared (FT-IR), and thermogravimetric analysis (TGA)). Based on the combined morphological, electronic, and structural features, the activity of the as-prepared CuO nanoparticles as a heterogeneous catalyst in Huisgen azide-alkyne cycloaddition was explored. This chemistry works well in water (green medium) by showing catalytic competence toward an array of structurally and electronically distinct alkynes/azides. The catalyst can be recovered and reused for six cycles without much significant loss in the morphology and nanocrystallinity and solution leach-out. The developed methodology can also be extended to the synthesis of fluorogenic clickates, which display attractive optoelectrochemical properties. High chemical yields, good atom economy, excellent regioselectivity, gram-scale synthesis, short reaction time, and no rigorous solvent extraction are some of the other noteworthy advantages from a sustainable chemistry perspective. Thus, the current approach is operationally benign with respect to not only catalyst preparation but also its subsequent applicability in click synthesis.