Dual synergistic and efficient catalytic activity of highly dispersed CuCo sulfides for the A³ reaction

Abstract

Highly active CuCo/S catalysts were designed for the propargylamine synthesis via the green A³ coupling reaction, in which the only by-product was H₂O. The CuCo/S catalysts were derived from Prussian blue structured CuCo-MOF by in situ sulfurization, and the exposure of surface Cu⁺/Cu⁰ active sites was strongly improved after the sulfurization treatment (Cu:Co atomic ratio: 0.404(MOF), 8.33(CuCo/S)). The CuCo/S catalyst showed excellent catalytic performance during propargylamine synthesis, and the conversion rate reached to 204 mmol·g⁻¹·h⁻¹. Moreover, the Cu and Co elements were highly dispersed in the CuCo/S composite, with catalytic performance superior to the physical mixture of CuS and CoS (CuS/CoS) in the same ratio. Control experiments indicated that the synergistic effect of multiple active sites in CuCo/S significantly promoted the activation of the C≡H bond at the alkyne terminus. Furthermore, the CuCo/S catalyst exhibited good stability with 85.9 % conversion after five cycles, with substrate expansion experiments confirming its broad applicability and sustainability.