Palladium-Catalyzed 1,2-Alkynylarylation of Vinyl Arenes with Haloalkynes and Arylboronic Acids

We herein disclose a novel palladium-catalyzed 1,2-alkynylarylation of vinyl arenes using haloalkynes and arylboronic acids as coupling partners. This reaction is characterized by broad substrate scope, controllable reaction sequence, and excellent chemo- and regioselectivities. Mechanistic investigations suggest that the reaction is initiated by regioselective insertion of vinyl arenes into the alkynyl-Pd(II) species, and the silver salt is crucial for this transformation, serving as both the Lewis acid and halide scavenger. This protocol provides efficient access to new carbon skeletons, which are embedded in the key biologically active motifs

Dirac Half-Semimetallicity and Antiferromagnetism in Graphene Nanoribbon/Hexagonal Boron Nitride Heterojunctions

Half-metals have been envisioned as active components in spintronic devices by virtue of their completely spin-polarized electrical currents. Actual materials hosting half-metallic phases, however, remain scarce. Here, we predict that recently fabricated heterojunctions of zigzag nanoribbons embedded in two-dimensional hexagonal boron nitride are half-semimetallic, featuring fully spin-polarized Dirac points at the Fermi level. The half-semimetallicity originates from the transfer of charges from hexagonal boron nitride to the embedded graphene nanoribbon. These charges give rise to opposite energy shifts of the states residing at the two edges, while preserving their intrinsic antiferromagnetic exchange coupling. Upon doping, an antiferromagnetic-to-ferrimagnetic phase transition occurs in these heterojunctions, with the sign of the excess charge controlling the spatial localization of the net magnetic moments. Our findings demonstrate that such heterojunctions realize tunable one-dimensional conducting channels of spin-polarized Dirac fermions seamlessly integrated into a two-dimensional insulator, thus holding promise for the development of carbon-based spintronics