INCLUSION OF ORGANIC VAPORS BY CRYSTALLINE HOSTS .4. CHEMICAL-SENSITIVE COATINGS FOR SENSOR APPLICATIONS

Solid inclusion hosts, such as derivatives of bis-fluorenyl (1, 2) and maleic acid (3), can include organic solvent vapour molecules such as acetone, cyclohexanone, methanol, ethanol, 1-butanol and dioxane to form stoichiometric inclusion complexes. Due to their ability to be used as gas-sensing layers, the absorption and desorption of acetone by crystalline host 1 is on-line monitored by a recording balance. For sensitivity improvement hosts 1 and 3 are coated onto the surface of a quartz crystal, the indicating device of the quartz microbalance. In the presence of various saturated vapour atmospheres we obtained reversible and reproducible signals within a short response time. Stoichiometrics of sorptive clathrate formations with 1-3 are determined by weighing. By differential scanning calorimetry (DSC) temperature dependence and enthalpies of guest desorption from host 1 can be determined, thus indicating weak host-guest interactions.