THE SOLID STATE LUMINESCENCE OF ESTROGENS

Abstract. The luminescent behavior of certain estrogens in the solid state is discussed. Spectra of solid films of estradiol and estriol are red shifted compared to that in liquid solutions with estriol shifted to a lesser extent. The red shifts are attributed to intermolecular hydrogen bonding, this conclusion being based on IR spectra and X-ray data. The calculated distance over which hydrogen bonding takes place is 2.755 Å in estradiol and 2.638 Å in estriol. The increased shift in the spectrum of estradiol is believed to be due to an additional hydrogen bond with a water molecule present in the solid film (O—O distance 2.793 Å). In estrone the weak fluorescence present in liquid solution is absent in solid film, in contrast to 3-desoxyestrone where fluorescence is preserved. Out of three possible forms of crystalline estrone only two can form hydrogen bonds, based on O-O distance calculations. In equilenin, which is highly fluorescent in liquid solution, no fluorescence is detected in solid film. This again is attributed to hydrogen bonding between the hydroxyl group of the β-naphtholic chromophore and the carbonyl group in the C(17) position. Dihydroequilenin which lacks the carbonyl group and equilenin dissolved in a host crystal retain their fluorescence.