MOLECULAR RECOGNITION OF ORGANIC-SOLVENTS AND AMMONIA - SHAPES AND DONOR PROPERTIES AS SENSOR EFFECTS

Chemically sensitive layers have been developed to characterize the donor properties and shapes of analytes by resistive and optical means. Macrocyclic nickel(II) complexes show substitution reactions with donor molecules. This behaviour is used as a model system for the detection of ammonia and the formation of mobile anions leads to increased conductivity. A detection limit in the ppm range can be achieved. Furthermore, cholesteric liquid crystals are able to distinguish molecules according to their morphological properties. The incorporation of the analyte leads to a shift of the absorbance maximum. The sensor characteristics reveal that these layers differentiate between homologous molecules, e.g., alcohols and hydrocarbons. Due to their shapes, these compounds give different sensor responses even at the same vapour pressure.