Design criteria for ionic liquid crystalline phases of phosphonium salts with three equivalent long n-alkyl chains.

The factors influencing the formation, organizations, and temperature ranges of the smectic phases of a structurally diverse family of phosphonium salts have been examined. The salts consist of one short group and three long n-alkyl chains attached to a positively charged phosphorus atom and either a free or covalently attached counterion, the latter resulting in zwitterionic salts. Of the 61 salts investigated, of which 37 have not been synthesized previously, most pack in lamellae within their solid phases.