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[摘要]：Fluorescence spectra of N-substituted 2-(2-aminophenyl)-4H-3,1-benzoxazin-4-ones consist of two bands, the long-wavelength band with anomalous Stokes shift, which corresponds to the emission of the product of intramolecular photoinduced proton transfer, and the short-wavelength band belonging to the form in which proton transfer does not occur. It is assumed that there is equilibrium between two planar rotamers in the ground state: one with the N-HaEuro broken vertical bar N hydrogen bond in which the intramolecular photoinduced proton transfer occurs and the other with the N-HaEuro broken vertical bar O bond, which does not experience hydrogen transfer. According to ab initio quantum-chemical calculations, the potential energy of proton transfer in the first excited singlet state has a potential barrier of 2.1-26.8 kJ/mol depending on the electron-withdrawing ability of the substituent on the amino group. |
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