Receptor molecules photopolymerizable

For the synthesis of a photopolymerizable receptor molecule that has a high selectivity for K+, we have modified the hemispherand synthesis according to Scheme 4. The final polymer membrane is represented by Figure 8. The response to a variation in K+ concentration (10 s - 10"1 M) in the presence of 0.1 M NaCl is given in Figure 9. The potentiometric selectivities (log K ) determined by the mixed solution method are -3.0 (Na+), -3.5 (Ca2+), -4.0 (Mg2+), and -0.7 (NH/). This renders this CHEMFET an excellent K+-sensor with a longterm stability t> 100 days). 

The positive results with the polysiloxanes as membrane materials directly deposited on the gate oxide led us to investigate these materials for our ultimate chemical system for the transduction of complexation reactions by FETs. This work is comprised of two parts viz. the synthesis of photopolymerizable siloxanes that can be covalently attached to the polyHEMA intermediate layer and the synthesis of receptor molecules that are selective for K+ which can be covalently incorporated in these membrane materials. For the deposition of the membranes on wafer scale via IC compatible technology, photochemical processes are a prerequisite. 

Until now, only a restricted number of photopolymerizable calix[4]arene-based receptor molecules are known. Calix[4]arene 42 showed to be selective for Na ions in the presence of different interfering ions [29]. More recently, we also synthesized... 

The receptor molecules and anionic sites containing photopolymerizable side groups were incorporated in the polysiloxane membrane. Covalent attachment of polysiloxane to the polyHEMA layer was achieved by prior methacrylation of part of the hydroxyethyl groups of polyHEMA. Subsequent photopolymerization yields a stable polymer network in which... 

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