Steroidal Aza-Lariat Ethers: Syntheses and Aggregation Behavior

Ten steroid-substituted lariat ether compounds have been prepared including one- and two-armed derivatives of aza-15-crown-5 and aza- and diaza-18-crown-6. They include, N-(3-cholesteryloxycarbonyl-methyl)-aza-15-crown-5, 1, N-(3-dihydrocholesteryloxycarbonylmethyl)-aza-15-crown-5, 2, N-(3-cholesteryloxycarbonylmethyl)-aza-18-crown-6, 3, N-(3-dihydrocholesteryloxycarbonylmethyl)-aza-18-crown-6, 4, N-(3-dihydrocholesteryloxycarbonylpropyl)-aza-15-crown-5, 5, N-(3-dihydrocholesteryloxycarbonylpentyl)-aza-15-crown-5, 6, N-(3-dihydrocholesteryloxycarbonylheptyl)-aza-15-crown-5, 7, N-(3-dihydrocholesteryloxycarbonyldecyl)-aza-15-crown-5, 8, N,N′-bis(3-cholestanyloxycarbonyl-methyl)-4,13-diaza-18-crown-6, 9, and N,N′-bis(3-cholestanyloxycarbonyldecyl)-4,13-diaza-18-crown-6, 10. Aqueous suspensions of these monomers were sonicated. Laser light scattering experiments showed that stable, vesicular aggregates formed. Dye entrapment experiments confirmed the vesicular nature of these aggregates in selected cases. Likewise, the effect of added salts (selected from among NaCl, KCl, BaCl 2 , 0-25 equivalents) on aggregate size was assessed. The results were found to agree with a theoretical model developed by Isralachvilli, Ninham, Evans and their coworkers.