Photoinduced Concerted Dual Single-bond Rotation of a Nitrogen-containing System Realized by Chalcogen Substitution

Conformational change caused by photochemical concerted multiple bond rotation is a very rare event. Thus, it is a critical challenge to expand this chemistry because it has higher potential to more precisely modulate the molecular function of molecules. Here, we describe a novel nitrogen-containing molecular system exhibiting photoinduced concerted rotation, which is the first example of successfully incorporating heteroatoms into a system exhibiting photoinduced concerted rotation. Sufficient kinetic stability and photosensitivity to realize photoinduced concerted rotation can be brought to a sterically hindered benzamide system by chalcogen substitution. The photoinduced C-N/C-C concerted rotation of the thioamide derivative can be directly observed, and it was found that the thioamide system exhibits the ability to generate different conformers depending on external stimuli. A theoretical study also supported the selective occurrence of photoinduced C-N/C-C concerted rotation. It is expected that the system can be utilized to modulate the functions of organic compounds.