Researchers led by Associate Professor Toyo Kazu Yamada from Chiba University have achieved a breakthrough in stabilizing ferrocene molecules on a substrate, paving the way for the development of an electrically controllable sliding molecular machine. Ferrocene, a unique molecule recognized for its Nobel Prize-winning discovery, becomes a suitable candidate for molecular machinery due to its structure, which allows a significant rotation of its carbon rings based on the iron ion’s electronic state. A major hurdle in ferrocene’s practical applications has been its instability when adsorbed onto surfaces, particularly noble metals. The team overcame this challenge by modifying ferrocene with ammonium salts to form ferrocene ammonium salts (Fc-amm) and anchoring them onto a crown ether film applied to a copper substrate. This layer acts as a protective shield, preventing decomposition. The sliding motion of molecules was activated by applying a voltage using scanning tunneling microscopy, causing a reversible shift in position as the iron ion transitioned between electronic states. The findings reveal exciting prospects for ferrocene-based machines, promising innovations in fields like molecular electronics, precision medicine, and advanced manufacturing. The research, published in the journal Small, marks a significant step in designing controllable molecular machinery.
