Abstract
The π-π* absorption spectra of some psoralens with skin photosensitizing action were measured in various solvents, up to vacuum ultraviolet region. We found that these compounds exhibit six π-π* bands within 180-400 nm region and the longest wavelength absorption band of psoralen shows a blue shift with increasing polarity of the solvents. Furthermore, the molecular orbital calculation of the π-electronic systems of psoralens were carried out by means of the Pariser-Parr-Pople method. The obtained absorption π-π* bands were assigned on the basis of the calculated results.
