Chem. Sci., 2025, Advance Article DOI: 10.1039/D5SC06085K, Edge Article Adila Adijiang, Yunlong Ge, Hefa Feng, Yan Yan, Xin Zuo, Haoyu Wang, Xueyan Zhao, Min Tan, Surong Zhang, Xiaona Xu, Lichuan Chen, Chuankui Wang, Zongliang Li, Dong Xiang The enol → keto tautomerism of β-diketones was realized by p-polarized UV irradiation at an extremely low intensity employing antenna electrodes, where the optical field is greatly enhanced and confined facilitating the tautomerism of one molecule at a time.