Thermal and structural study of the crystal phases and mesophases in the lithium and thallium(I) propanoates and pentanoates binary systems: Formation of mixed salts and stabilization of the ionic liquid crystal phase

Article abstract of DOI:10.1021/jp1031702

The temperature and enthalpy vs composition phase diagrams of the binary systems [xC₂H₅CO₂Li + (1 - x)C ₂H₅CO₂Tl], and [x(n-C₄H ₉CO₂Li) + (1 - x)n-C₄H₉CO ₂Tl], where x is the mole fraction, were determined by DSC. Both binary systems display the formation of one 2:1 mixed salt each (at x = 0.667) that appear as a peritectic (incongruent melting) at T_fus = 512.0 K, and T_fus = 461.1 K, with ??_fusH_m = 13.76 and 8.08 kJ?·mol^-1 for Li-Tl (I) propanoates, and n-pentanoate mixed salts, respectively. The thermotropic liquid crystal of the thallium(I) n-pentanoate transforms into a more stable liquid-crystal phase, which appears in the phase diagram between 380 and 488 K and for x = 0 up to x = 0.56. The crystal structure of thallium(I) propanoate and of the two mixed salts were obtained via X-ray synchrotron radiation diffraction measurements. These compounds present a bilayered structure similar to the two pure lithium salts previously found by our group. ? 2010 American Chemical Society.