Deskarene: Single-Molecule Conductance and Mixed-Valence Character of Diferrocene-Based Ladder-Type Conjugated Molecules

Ferrocene–anthracene-fused ladder-type molecules (2Fc-anti and 2Fc-syn) were achieved via a C–H activation/annulation strategy. This design extends the π-conjugated system through molecular ladderization, effectively elongating the molecular backbone and enhancing its delocalization. 2Fc-anti exhibits characteristic class II mixed-valence behavior, with superior equilibrium constant Kc compared to the non-ladderized control molecule 2Fc-nc. Single-molecule conductance measurements using the scanning tunneling microscopy break junction (STM-BJ) technique identified the most probable conductance of 10–3.3 G0, indicating that the molecular framework possesses efficient charge transport capability.