Polyphenylene Dendrimers as Sensitive and Selective Sensor Layers This work has been supported by the TMR European Research Program, through the SISITOMAS Project, by the Volkswagen Foundation, the German Science Foundation (DFG), the German Federal Ministry for Science and Technology (BMBF), and the Fonds of the German Chemical Industry, Frankfurt (Main); U.M.W. thanks the latter for a graduate fellowship, we all thank C. Beer and S. Spang for valuable support during the syntheses.