Neutral Anion Receptors:  Synthesis and Evaluation as Sensing Molecules in Chemically Modified Field Effect Transistors

Abstract

A new class of anion selective receptors is based on the neutral uranylsalophene building block as Lewis acidic binding site. Additional hydrogen 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 selectivities that strongly deviate from the classical Hofmeister series favoring phosphate or fluoride anions, depending on the structure of the uranylsalophenes. The phosphate selective chemically modified field effect transistors (CHEMFETs) detect phosphate with high selectivity over much more lipophilic anions, such as nitrate (log = −1.3), at [H2PO4-] ≥ 6.3 × 10-4 M. CHEMFETs modified with salophenes with amido substituents result in a high fluoride selectivity; even in the presence of 0.1 M chloride, fluoride can be detected at [F-] ≥ 6 × 10-4 M (log = −2.0).