Symmetry-Breaking in Carbon Nanohoops Enables Room-Temperature Ternary Single-Molecule Switching

Single-molecule electronics offers chemically encoded routes to ultra-dense information processing, yet room-temperature operation is often limited to binary conductance states due to thermal broadening and electronic averaging. Here we demonstrate robust ternary switching at room temperature using symmetry-engineered carbon nanohoops. Embedding a pyrene unit into the [12]cycloparaphenylene backbone via a symmetry-breaking 1,6-linkage disrupts the electronic equivalence of π-segments and localizes frontier orbitals. Under controlled mechanical elongation in single-molecule junctions, the molecule exhibits three well-resolved conductance plateaus, each separated by ∼one order of magnitude, affording unambiguous and reproducible readout. First-principles transport calculations reveal that symmetry-breaking-induced orbital localization discretizes coherent tunneling pathways, accounting for the observed plateaus. These findings establish molecular symmetry control as a general design principle for room-temperature multistate charge transport in conjugated macrocycles, opening a pathway to high-density single-molecule logic architectures.