Iminyl-Radical-Mediated Formation of Covalent Au–N Bonds for Molecular Junctions
Mingliang Zhang, Junfeng Lin, Kai Song, Kaili Chang, Xiaojuan Dai, Yaping Zang, Daoben Zhu
Abstract
The interaction between organic radicals and transition metals plays a crucial role in radical-mediated chemical reactions, functional devices, and biocatalysis. Characterizing such interactions, however, remains a long-standing challenge due to the inherently high reactivity of radical species. Here, using a scanning tunneling microscope breaking junction (STM-BJ) technique, we are able to detect the interaction mode between iminyl radicals and the gold surface at a single molecule level. We show that the free iminyl radicals generated through photochemical N-O bond homolysis of oxime esters react toward the gold electrode surface and produce covalent Au-N bonds. Intriguingly, we find that the Au-N bonding reactions lead to the formation of robust and highly conductive single-molecule junctions. These findings provide not only insights into the mechanism of iminyl-radical-involved reactions but also a facile photolysis method to create a new type of covalent electrode-molecule bonding contact for molecular devices.