NEUTRAL ANION RECEPTORS - SYNTHESIS AND EVALUATION AS SENSING MOLECULES IN CHEMICALLY-MODIFIED FIELD-EFFECT TRANSISTORS

A new class of anion selective receptors is based on the neutral urany lsalophene building block as Lewis acidic binding site. Additional hyd rogen bond accepting or donating moieties near the anion binding site offer the possibility of varying the binding selectivity. Field effect transistors chemically modified with such receptors exhibit anion sel ectivities that strongly deviate from the classical Hofmeister series favoring phosphate or fluoride anions, depending on the structure of t he uranylsalophenes. The phosphate selective chemically modified field effect transistors (CHEMFETs) detect phosphate with high selectivity over much more lipophilic anions, such as nitrate (log K-H2PO4,NO3(Pot ) = -1.3), at [H2PO4-] greater than or equal to 6.3 x 10(-4) M. CHEMFE Ts modified with salophenes with amido substituents result in a high f luoride selectivity; even in the presence of 0.1 M chloride, fluoride can be detected at [F-] greater than or equal to 6 x 10(-4) M (log K-F ,Cl(Pot) = -2.0).