UV photoelectron spectroscopy of coumarins

The electronic structure and other properties of 21 coumarin derivatives have been investigated by a combination of experimental and theoretical methods: UV photoelectron spectra (UPS), UV/VIS spectroscopy and semi-empirical MO calculations. The influence of substituents on the properties of coumarin derivatives is discussed and some predictions of unknown properties are made. One of our coumarins has the lowest ionization energy (6.87 eV) yet reported for any coumarin.