Reaction with organic halides as a general method for the covalent functionalization of nanosheets of 2D chalcogenides and related materials

Prompted by the success in functionalizing 2D sheets of MoS2 and MoSe2 by their reaction with organic halides, we have investigated the functionalization of layered tungsten chalcogenides, WS2, WSe2, and WTe2, by their reaction with substituted iodobenzenes as well as fluorophores based on pyrene and coumarin. Carbon-chalcogenide bonds are formed readily in the case of metallic chalcogenides while there is need for the Pd(0) catalysts in the case of insulating chalcogenides. Thus, the formation of carbon-chalcogen (S, Se, and Te) bonds is accomplished with the metallic 1T as well as the semiconducting 2H phases of the tungsten chalcogenides. Functionalization in the case of substituted iodobenzenes is favored by the electron withdrawing groups in the benzene ring. Interestingly, functionalization has been successful with other insulating layered chalcogenides such as GaS and GaSe. Reaction with organic halides emerges as a general method for the covalent functionalization of chalcogenide nanosheets, suggesting the possible use of this strategy to functionalize various chalcogenide structures.