Fluorescence sensing behavior of crystals of an imidazole-type clathrate host upon contact with gaseous carboxylic acids

The crystals of the title fluorescent clathrand exhibit a drastic fluoresce nce enhancement behavior upon contact with carboxylic acid vapors. The magn itude of the fluorescence change is greatly dependent on the enclathrated c arboxylic acid molecules and increase in the following order: formic acid < acetic acid < propionic acid. To elucidate the enclathrated guest effects on the fluorescence properties of the crystals, the X-ray crystal structure s have been determined.