MONOLAYER PROPERTIES OF 1,1'-(1,OMEGA-TETRADECANEDIYL)BISPYRIDINIUM ALKANESULFONATES SPREAD ON THE CONCENTRATED-SOLUTIONS OF ELECTROLYTE

The surface pressure (π) and the surface potential (ΔV)-area (A) isotherms for monolayers of double long-chain salts of 1,1′-(1,ω-tetradecanediyl)bispyridinium with five different alkanesulfonates on water and on 4.4 M aqueous solutions of electrolyte were measured at various temperatures by the Langmuir method. Some π-A curves of these salts showed two transition points. Judging from the surface potential, the apparent molar entropy, and previous data on the transition [Bull. Chem. Soc. Japan 60, 3077 (1988)], the first was assigned to the transition from the expanded state (E phase) to the condensed state (C-I′ phase) and the second from the C-I′ phase to another condensed state (C-II phase). There exists a triple point on the phase diagram at which three phases (E, C-I′, and C-II) coexist. From the surface potential, the apparent molar entropy change, and phase diagram, the orientation of double long-chain salts in the monolayer state was also discussed. © 1991.