CuS-MoS2 nanosheet-catalyzed selective oxidative azo-coupling of anilines.

Cu containing MoS2 nanosheets were synthesized via a facile hydrothermal method and employed as an efficient heterogeneous catalyst for oxidative azo-coupling of aromatic amines. Structural and morphological characterisation (PXRD, FTIR, SEM-EDX, ICP-MS, HRTEM and XPS) confirmed the successful formation of a CuS-MoS2 composite. ∼18 wt% Cu is present in the CuS-MoS2 as indicated by EDX and ICP-MS, whereas XPS confirmed the presence of a predominant Cu+ state together with Cu2+. The catalyst demonstrated excellent activity, affording a wide range of azo compounds in high yields (75-96%) with outstanding chemoselectivity under mild conditions using TBHP as an oxidant. Both homo- and hetero-coupling reactions proceeded efficiently. The enhanced catalytic performance is attributed to the synergistic interactions between Cu species and the MoS2 support, which promotes effective charge transfer and redox cycling. The catalyst is recyclable for up to 7 cycles without significant loss of activity and is used in gram-scale synthesis. This work provides a simple, robust, sustainable, and cost-effective catalytic system, expanding the utility of metal-doped MoS2 materials in selective organic transformations.