Curvature-Directed Selective C–C Bond Cleavage Driven by Electric Fields

Controlling chemical reactivity through molecular strain offers a compelling strategy for precision bond manipulation at the single-molecule level. Here, we show that spatially differentiated curvature in a nonplanar <i>π</i>-conjugated system can program the site of carbon-carbon (C-C) bond cleavage without the need for catalysts or harsh conditions. Using a teardrop-shaped carbon nanohoop (<i>meta</i>-cycloparaphenylene, <i>m</i>CPP) with an intrinsic curvature gradient, we achieve highly selective C-C bond scission at the most strained site by applying a mild electrical bias (∼1 V) via the scanning tunneling microscopy break-junction (STM-BJ) technique. With a predominant product yield of ∼75%, the process produces linear oligophenylene junctions featuring well-defined Au-C <i>σ</i> contacts. Remarkably, the curved molecular architecture defines a postcleavage transport pathway that inherently exhibits destructive quantum interference (DQI), leading to conductance suppression by over 4 orders of magnitude. These findings introduce molecular curvature as a programmable design element for guiding bond activation and tailoring charge transport in <i>π</i>-electronic systems.