| Abstract
| - A quartz crystal microbalance (QCM) spray-coated witha Ni(SCN)2(4-picoline)4 film is asensitive detector forsmall aromatic (benzene, toluene) and chlorinated (trichloroethylene, perchloroethylene) vapors with a planar molecular geometry. Frequency changes during transientexposures to these vapors are rapid and reversible.Incontrast, frequency changes during transient exposuresto carbon tetrachloride vapor exhibit a very slow rise anddecay. Impedance studies demonstrate that the QCMsare responding only to mass changes in the film.Calibration curves exhibit both linear and near-saturation responses, depending on the vapor and vapor concentration. Partition coefficients obtained from the linearresponse regimes of the calibration curves are in the10 000−100 000 range, more than an order of magnitude larger than the partition coefficients for aprototypicalsoft polymer, poly(isobutylene). Despite the absenceofevidence for crystallinity by optical or X-ray diffractionmethods, the spray-coated films appear to be formingclathrates with the organic vapors. TheNi(SCN)2(4-picoline)4 film is promising for the development ofverysensitive and partially selective piezoelectric sensorsfornonpolar or weakly polar organic vapors in air.
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