Microporous organic-inorganic nanocomposites as the receptor in the QCM sensing of toluene vapors.

We have used novel microporous biphenylene-pillared layered silicates as receptors in a quartz crystal microbalance (QCM) for sensing toluene vapors. The silicate was successfully coated on a QCM electrode modified with 2-aminoethanethiol. The resultant electrode showed quantitative frequency responses due to enhanced adhesion between the silicate and the electrode. The silicate-coated electrodes also performed better than polystyrene-coated electrodes in terms of both sensitivity and reproducibility of the responses for toluene vapors exposures because the silicate has an organically-modified open-framework structure with a high surface area. In addition, the electrodes revealed the higher sensitivity for toluene vapors than those for alcohol vapors, suggesting selectivity toward sensing toluene vapors probably due to the π-π stacking interaction between biphenylene units and toluene molecules. Hence, we anticipate that the materials are promising to be used as receptors in QCM devices for sensing aromatic vapors.