Bimetallic Ionic Liquid-Derived Co-Zn-NC Nanocatalysts: Efficient Oxidative Coupling of Indoles and Thiophenols under Mild Conditions

In this study, a series of bimetallic ionic liquid-derived Co-Zn-NC nanocatalysts with hollow nanotubular mesoporous nanostructures were successfully synthesized. These catalysts, containing both graphite-encased cobalt nanoparticles (Co NPs) and cobalt single-atom sites (Co SAs), were systematically investigated for their performance in the aerobic oxidative C–S coupling reactions of indoles and thiophenols. Detailed characterization via XRD, TEM, XPS, BET, and other techniques was conducted to analyze the structural and chemical properties of the catalysts. The results demonstrated that the Co-Zn (1:4)-NC nanocatalysts exhibited excellent catalytic activity under optimized reaction conditions (DMSO as solvent, 0.2 eq. NaOH as base, 1 atm O2, 80 °C, 17 h), achieving high yields for various substrates. Moreover, the catalyst showed good stability and recyclability, maintaining high activity even after six cycles. This work provides an efficient, mild, and sustainable approach for the synthesis of 3-sulfenylindole derivatives, highlighting the critical role of nanoscale structural engineering in boosting catalytic performance, with potential applications in organic synthesis, especially in the pharmaceutical field.