σ-hole effect of halogen-bonded cocrystals causing tunable photoelectric properties for photocatalytic uranium removal

Abstract

The mechanism of how the internal composition of halogen-bonded cocrystals affecting photoelectric properties is ambiguous. Herein, we report a series of stable halogen-bonded cocrystals containing I-, Br-based halogen bond donors and N-based halogen bond acceptor. The halogen bonds served an intrinsic hub, and the two parts (donor and acceptor) were spliced into a highly ordered periodic network with a tight electronic configuration. The charge transfer within lattice induced by the σ-hole effect activates disparate photoelectric phenomena. The results uncover that the degree of photoelectric response of cocrystals can be adjusted rationally by manipulating the intensity and density of σ-holes with an atomic precision at the molecular level. The experimental and theoretical studies of the σ-hole effect pave the way to simplify the design principle of functional cocrystals. Eventually, benefiting from the fascinating photoelectric activity, halogen-bonded cocrystals exhibited excellent photocatalytic reduction ability of radionuclide uranium.