The substituent effect on the excited state intramolecular proton transfer of 3-hydroxychromone
Song Yuzhi †, Liu Songsong, Lu Jiajun, Zhang Hui, Zhang Changzhe, Du Jun ‡
       

IR spectra for the O–H bond of (a) FM, (b) BFM, (c) BFBC, and (d) CCM.