Molecularly imprinted polyurethanes are presented as sensitive coatings for the detection of polycyclic aromatic hydrocarbons in water. These sensor layers were combined with fluorescence and mass-sensitive transducers. Imprinting based on van der Waals interactions allows detection of these analytes even without any pronounced functionality. The geometry of the imprint molecule determines the selectivity of the sensor layer. In varying the size of template molecules from anthracene up to 1,12benzoperylene, selectivity is tuned to a distinct analyte. The enrichment factor of up to approximately 10 7 renders detection down to the ppt range possible with hardly any matrix effect by humic acids.

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17] The maximum loading of 1 into the MCM-41 was determined by making several samples of MCM-41 with increasing loadings of monomer until an excess of monomer was present. This occurred at approx. 74 wt.-% (estimated standard deviation (esd) 5 %) 1 in calcined MCM-41. All samples prepared with larger quantities of 1 had an excess of 1 that was removed by sublimation. Given an estimated porosity of 1±1.2 cm 3 g ±1 for MCM-41, this seems to be a reasonable loading. The ca. 45 % loaded sample contains approximately 45 % of the determined maximum loading. See the Experimental section for details of how the ca. 45 % loaded and the fully loaded samples were prepared.[18] These NMR assignments at low loadings are consistent with those published by O'Hare and coworkers for the surface derivatization of MCM-41 using a pentane solution of 1 (see [16b]).Chemical sensors [1] are successfully used to monitor air quality, for example, for emission control. Consequently, air pollution is continuously being reduced, but the toxic agents intercepted are increasingly being deposited elsewhere. After deposition, the pollutants contaminate ground water. Therefore the monitoring of harmful substances in liquid media, for example, in seepage water, is becoming more and more important in environmental analysis. This is especially true of the toxic and carcinogenic polycyclic aromatic hydrocarbons (PAHs) [2] that form in incomplete combustion processes, for example, in diesel engines.Because of its high sensitivity, fluorescence spectroscopy [3,4] is a suitable technique for the detection of PAHs.Online measurements in the range of maximum permissible values are favorable and are achieved by improved sensitivity through the use of laser fluorescence and chemical sensor layers. The sensitive coatings can enrich the concentration of the analyte and both sensitivity and selectivity are optimized by chemical recognition. Pyrene and anthracene are used here as test analytes for the evaluation of the potential of this method. Supramolecular compounds, for example, molecular cavities, [5] are promising materials in sensor design in combination with both microelectronic devices and optical detection principles. However, complex synthesis is necessary to generate these host molecules. The technique of molecular imprinting [6±8] opens up new prospects as these materials can be directly generated on the transducer by polymerization in the presence of the analyte, which is efficiently extracted even from complex matrices. [9] After completion of this on-chip polymerization reaction, the template molecules are removed by dissolution. Diffusion pathways and adapted cavities ideally suited to the analyte's reinclusion are left behind. Improved properties as regards mechanical stability, insolubility, and chemical inertness in the case of in-liquid-sensing are accomplished. In the the case of PAHs no pronounced functionality exists and therefore the imprinting process is performed through all kinds of noncovalent interactions, summarized as van der W...

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