Molecular Cage-Shielded Copper(I) with Exceptional Stability and Enhanced Anti-Corrosion Performance

Cu(I) species are inherently labile under ambient conditions, limiting both their fundamental study and practical applications. Here, we report a molecular cage-based strategy for stabilizing Cu(I) through coordination with imine-bearing organic hosts. The resulting complex displays exceptional long-term stability─not only in aqueous solution and ambient air but also under strongly acidic, basic, and redox conditions─retaining its integrity for up to 1 year. This stabilization arises from a cooperative effect between Cu(I) and the imine groups, which are themselves typically unstable under such harsh conditions. Mechanistic studies reveal that strong Cu–imine bonding within the cage, along with a hydrophobic microenvironment provided by the surrounding counteranions, is key to preserving the complex. Beyond molecular stabilization, this system enables anticorrosion treatment of Cu foil via cage-mediated surface solvation, forming an ultrathin passivation layer that maintains electrical conductivity while enhancing resistance to oxidative degradation in alkaline environments. These findings offer a new platform for stabilizing reactive metal species and advancing corrosion-resistant materials.