Dynamic Regulation of Adaptive Butterfly-Shaped Molecules via B←N Coordination.

Abstract

Achieving dynamic control over stereostructures and electronic properties of rigid molecules remains a significant challenge due to the delicate balance between stability and flexibility. Here, the construction of butterfly-shaped molecular junctions stabilized by moderate-strength boron-nitrogen (B←N) coordination between boraacenes and pyridines is reported. By leveraging the pivot-like flexibility of B←N bonds, molecular conductance switching with on/off ratios exceeding 100 is achieved through force-driven dynamic transitions between distinct stacking conformations. Single-molecule electrical measurements combined with first-principle calculations identify distinct charge transport mechanisms-through-space and through-bond-associated with the butterfly-wing open and closed configurations. Furthermore, external factors like electric fields and substituent effects modulate π-π interactions and charge transport properties. The introduction of destructive quantum interference effects can be achieved by replacing molecular units. The findings demonstrate that B←N coordination serves as a dynamically tunable linkage, offering a pathway to design molecular platforms with multifunctional units, customized stereo-conformations, and quantum effects.