Enhancing π-π stacking by a halogen substituent in a single-molecule junction

Modulating π-π interactions and understanding their impact on charge transport at the molecular scale are critical for advancing supramolecular electronics. Herein, anthracene-based molecular wires (Py-X, X = H, F, Cl, Br) were synthesized and the effect of halogen substituents on π-π stacking was investigated. Experimental results revealed that Py-Br and Py-Cl form both monomer and π-stacked dimer junctions, while Py-H and Py-F only form monomer junctions. The bromine substituent demonstrates a unique ability to promote π-stacked dimer formation. This work provides a design strategy for the formation of π-stacked dimmers in molecular junctions, and advances the development of supramolecular electronics.