Synthesis of novel uranyl salophene derivatives and evaluation as sensing molecules in chemically modified field effect transistors (CHEMFETs)

Abstract

Several anion receptors have been synthesized based on the uranyl salophene moiety. The binding selectivity of the receptors can be influenced by substituents near the uranyl binding site of the receptor, which change the electron density of the uranyl center, the lipophilicity of the binding cleft, or provide sites for hydrogen bonding. The differences in binding selectivity are reflected in the selectivity of potentiometric sensors (chemically modified field effect transistors, CHEMFETs) developed with these receptors. The use of a uranyl salophene derivative with phenyl substituents near the binding site yields acetate selective sensors with selectivity over much more lipophilic anions like Cl^– and Br^– (log K ^Pot_AcO,j = –1.2). Lipophilic N-octanamido substituents near the uranyl center provide F^– selective CHEMFETs. The presence of urea moieties in the proximity of the binding site results in an even stronger F^– binding receptor which yields CHEMFETs which can detect F^– even in the presence of a 150-fold excess of the very lipophilic SCN^– anion (log K ^Pot_F,SCN = –2.2).