Properties of Langmuir monolayers of newly synthesized sensitizer-donor dyads containing a naphthalene and a ferrocene moiety

Abstract

Two sets of amphiphilic sensitizer (S)-donor (D) dyad molecules and their reference compounds were newly synthesized by a new synthetic route. In the S-D dyads, two functional moieties were linked together with a saturated hydrocarbon chain containing the number of carbons of 4. In these compounds, a naphthalene and a ferrocene moiety act as S and D, respectively. The naphthalene or the ferrocene moiety was further linked to another alkyl chain terminated with a carboxyl group,-COOH, to form amphiphilic S-D dyads. The carboxyl group dissociates into a carboxylate anion and acts as a hydrophilic anionic head group. The stability of the monolayers of these anionic amphiphiles was increased by polyion complexation with a polycation added in the aqueous subphase in comparison with calcium salt formation. Ion complexation (1:1) of each anionic amphiphile with a cationic surfactant, octadecyl ammonium, was also performed at the air-water interface by spreading a chloroform solution of a 1:1 surfactant mixture. The resulting mixed monolayer was also substantially stable.