“…Extensive X-ray studies on arylpropoxinolamine fl-blockers reveal a uniformity of the conformation of the propoxinolamine chain in the crystalline state (Ammon, Howe, Erhardt, Balsamo, Macchia, Macchia & Keefe, 1977;Barrans, Cotrait & Dangoumau, 1973;Carpy, Gadret, Hickel & Leger, 1979: Gadret, Goursolle, Leger & Colleter, 1975a,b, 1976aKido, Nakagawa, Fujiwara & Tomita, 1981;Kobelt & Paulus, 1974;Leger, Colleter & Carpy, 1982;Leger et al, 1977;Weber & Petcher, 1977). In general, these studies have been done on the ionic form because the arylpropoxinolamines are extensively protonated in the physiological environment (Sinistri & Villa, 1962); this implies that fl-blockers are probably protonated when bound and that they are recognized by an anionic or hydrogen-bonding site.…”