Thermotropic Mesomorphism of Mixed-valent Diruthenium Aliphatic Carboxylates with axial anion bearing two aliphatic chains

TAMARA BOTTAZZI; CECCHI, FLORENCIA; ZELCER, ANDRÉS; HEINRICH, BENOIT; DONNIO, BERTRAND; GUILLON, DANIEL; CUKIERNIK, FABIO D.

JOURNAL OF COORDINATION CHEMISTRY

TAYLOR & FRANCIS LTD

Lugar: Londres; Año: 2013 vol. 66 p. 3380 - 3390

0095-8972

A homologous series of binuclear mixed-valent diruthenium tetracarboxylates of formula Ru2(O2C(CH2)n-2CH3)4DHDP (DHDP = di(hexadecyl)phosphate axial anion, n = 10, 12, 14, 16 and 18) has been synthesized and characterized, and the liquid-crystalline properties of these compounds have been examined. All the studied compounds exhibit a room temperature lamellar crystalline phase and a high temperature (above 140º) Colh mesophase. Another, probably semi-crystalline, lamellar intermediate phase has also been found for all the studied compounds but n = 18 derivative. Comparison with related mesogenic homologous series where the equatorial ligands are also linear carboxylates, but the axial anions bear just one aliphatic chain (carboxylates, octylsulfonate, dodecylsulfate) show that the presence of a second aliphatic chain in the axial anion both lower transition temperatures and modifies the nature of the intermediate lamellar phase. Structural models at the molecular level are suggested for the crystalline lamellar and the Colh phases.