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 f orm stoichiometric inclusion complexes. Due to their ability to be use d as gas-sensing layers, the absorption and desorption of acetone by c rystalline host 1 is on-line monitored by a recording balance. For sen sitivity improvement hosts 1 and 3 are coated onto the surface of a qu artz crystal, the indicating device of the quartz microbalance. In the presence of various saturated vapour atmospheres we obtained reversib le and reproducible signals within a short response time. Stoichiometr ics of sorptive clathrate formations with 1-3 are determined by weighi ng. By differential scanning calorimetry (DSC) temperature dependence and enthalpies of guest desorption from host 1 can be determined, thus indicating weak host-guest interactions.