Conductivity properties of thiourea- and urea-halogen inclusion compounds with diquinuclidinium cation as guest

• JUAN MERCHAN ^[1] ; VLADIMIR LAVAYEN ^[2] ; PAUL JARA ^[2] ; VICTOR SANCHEZ ^[3] ; NICOLAS YUTRONIC ^[2]
  1. [1] Universidad Tecnológica Metropolitana

     Universidad Tecnológica Metropolitana

     Santiago, Chile

     
  2. [2] Universidad de Chile

     Universidad de Chile

     Santiago, Chile

     
  3. [3] Universidad Católica del Norte

     Universidad Católica del Norte

     Antofagasta, Chile

     

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• Localización: Journal of the Chilean Chemical Society (Boletín de la Sociedad Chilena de Química), ISSN-e 0717-6309, ISSN 0366-1644, Vol. 53, Nº. 2, 2008, págs. 1498-1502
• Idioma: inglés
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• Resumen

  • Thiourea and urea can modify their typical host properties to form new ternary polymolecular anionic halogen hosts in which the diquinuclidinium cation is included. A comparative study of the proton conductivity properties of this kind of inclusion compounds is presented. The hexagonal binary inclusion compound [quinuclidine]3thiourea 1 was taken as reference. The study shows the conductivity properties of [quinuclidine2H]+[thiourea2Cl]-2, [quinuclidine2H]+[thiourea2Br]- 3, [quinuclidine2H]2(2+)[thiourea2I2]2- 4, [quinuclidine2H]+[urea5Cl]- 5, [quinuclidine2H]+[urea2Br]- 6, and [quinuclidine2H]+[urea2I]- 7. Ionic conductivities of all the compounds in pellets, and of 2 and 3 in large single crystals were measured by electrochemical impedance spectroscopy (EIS). Anisotropic conductivity behaviour in crystals of adequate dimensions of 2 and 3 was detected. The conductivity values of 2 and 3 in the crystals were 2.19x10-4 and 6.03x10-6(S/cm), respectively, in the assµmed channel direction, and 2.42x10-6 and 8.27x10-9 (S/cm), respectively, in the perpendicular direction to the former, at 298 K. Conductivities at room temperature of the thiourea-halide derivatives in pellets show a changing behaviour from insulator (10-11 S/cm) for 2,3 and 4 measured in vacuµm, to semiconductor (10-7-10-8S/cm) for the thiourea-halide derivative measured at atmospheric pressure. For the urea-halide system the highest conductivity value corresponds to derivative 7 (8.66x10-5 S/cm) at atmospheric pressure, and the lowest to derivative 5 (5.48x10-7 S/cm) measured in vacuµm. Comparisons considering structural aspects are also discussed.