Junwoo Park's team and Yuan Li's team developed a molecular memristor using self-assembled monolayers (SAMs) of bipyridine–cobalt complexes that exhibit electric field-induced conformational switching, enabling synaptic behavior with ultralow energy consumption of 23.3 fJ·molecule?1. Conductance modulation arises from charge injection into the LUMO, triggering C–C bond rotations in the alkyl backbone. The device demonstrates paired-pulse facilitation, spike-dependent plasticity, and 90% accuracy in MNIST pattern recognition. Remarkably, it combines memristive and rectifying functions, supporting large-scale selector-free crossbar arrays. This work showcases how molecular conformational control can advance neuromorphic computing toward highly integrated, low-power systems.