UiO-67 MOF-Encapsulated\nNHC-Based Single-Site Copper\nCatalyst and Its Application in Regioselective Borylation of Terminal\nAlkynes

N-Heterocyclic\ncarbenes (NHCs) act as versatile ligand backbones\ndue to their strong σ-donation and π-acceptance properties.\nHowever, the encapsulation of NHC–coinage metal complexes in\na metal–organic framework (MOF) to utilize them in organic\ncatalysis is rare. In this work, an NHC-coordinated CuBr (NHC = Bn<sub>2</sub>Im; 1,3-dibenzyl-imidazol-2-ylidene) complex was encapsulated\nin UiO-67 MOF ((Bn<sub>2</sub>Im)<sub>2</sub>CuBr@UiO-67) and further\nutilized toward the regioselective protoboration of terminal alkynes.\n(Bn<sub>2</sub>Im)<sub>2</sub>CuBr@UiO-67 was found to show superior\ncatalytic performance in aiding the protoboration of terminal alkynes,\nwith a very high turnover frequency (TOF) of 14333.3 h<sup>–1</sup>, much higher than those of many other reported copper-based heterogeneous\ncatalysts. Our catalyst also retained excellent catalytic efficiency\nfor up to five cycles for the above-mentioned process. The newly synthesized\n(Bn<sub>2</sub>Im)<sub>2</sub>CuBr@UiO-67 and the recovered catalyst\npost-catalysis\nwere characterized using various analytical techniques,\nincluding powder X-ray diffraction (PXRD), IR spectroscopy, field-emission\nscanning electron microscopy (FESEM), high-resolution transmission\nelectron microscopy (HRTEM), and X-ray photoelectron spectroscopy\n(XPS).