Switching on H-Tunneling through Conformational Control

H-tunneling is a ubiquitous phenomenon, relevant to fields from biochemistry materials science, but harnessing it for mastering the manipulation of chemical structures still remains nearly illusory. Here, we demonstrate how switch on by conformational control using external radiation. This outlined with triplet 2-hydroxyphenylnitrene generated in an N2 matrix at 10 K UV-irradiation azide precursor. The anti-orientation nitrene’s OH moiety was converted syn selective vibrational excitation 2?(OH) frequency, thereby moving H atom closer vicinal nitrene center. triggers spontaneous singlet 6-imino-2,4-cyclohexadienone. Computations reveal that such fast occurs through crossing triplet-to-singlet potential energy surfaces. Our experimental realization provides exciting novel strategy attain over tunneling, opening new avenues directing transformations.