No abstract

No abstract

No abstract

The photoreactive states of skin-sensitizing-carcinogenic psoralens (furocoumarins) are characterized by the configuration analysis method of Baba and coworkers. The S, (n, n*) states of coumarin and psoralen possess significant charge transfer (CT) character in the C==C bond of the pyrone moiety (32% CT to the C 4 vacant orbital in coumarin and 22% in psoralen) and in the C==€ bond of the furyl moiety (4% CT to the vacant C==C orbital and 14% CT from the occupied C==C orbital in psoralen). On the other hand the TI (n, n*) state of these molecules shows a substantial localization of the excitation in the pyrone C 4 bond, thus providing a logical basis for the structure-activity correlation of skin-sensitizing coumarins. MethodsConceptually speaking, the CA method makes it possible to express the SFC CI wave functions of the molecule in question in terms of the corresponding wave functions of "reference" orbitals. Details of the CA procedure are given in [la], and are not repeated here, except for the final step of the CA formalism. 1

No abstract