CRYSTAL-STRUCTURE AND HORMONAL ACTIVITY OF 1,1-BIS(4-HYDROXYPHENYL)-2-PHENYLETHENE

A complete three-dimensional X-ray crystal structure analysis of 1,1-b is(4-hydroxyphenyl)-2-phenylethene (BHPE) has been carried out. Reflex es were collected at room temperature. After isotropic refinement of F -values by least-squares, R is 0.163. BHPE crystallizes with 8 molecul es in a unit cell of monoclinic symmetry, space group C2/c and cell di mensions a = 20.85 1, b = 15.505, C = 10.536 angstrom, beta = 107.54-d egrees. The molecule of BHPE is not flat, the aromatic rings are twist ed out of the ethene plane with angles of - 30.16-degrees (ring B), - 51.45-degrees (ring C) and - 33.49-degrees (ring A). The bond angle be tween the 1,1-standing, 4-hydroxy-substituted phenyl rings amounts to 115.3-degrees resulting in a distance between the hydroxy groups of 9. 636 angstrom. BHPE proved to be a weak ''impeded'' estrogen with minor antiestrogenic potency, though its estrogen receptor affinity is very high (29%, estradiol 100%). A discussion of the influence of the spat ial structure of BHPE and related substances on its estrogenic/antiest rogenic and mammary tumor-inhibiting potency is given.