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).

Artificial Receptors for the Recognition of Phosphorylated Molecules

“…664 These FETs were found to sense dihydrogenphosphate with selectivity observed relative to nitrate, bromide, chloride, and sulfate. The lowest detection limit (1.6 × 10 -4 M) was observed with receptor 605b , which may form hydrogen bonds between the methoxy groups and the phosphate.…”

Synthesis and Electrochemical Properties of Tetrasubstituted Tetraphenylethenes

“…[22] In contrast, 1c was easily nitrated in CH 2 Cl 2 to afford the desired tetrakis(nitrophenyl)ethene 1d in 60 % (Scheme 2). Attempts to reduce the nitro groups by using Pd/C, hydrazine, [23] Sn/HCl or SnCl 4 and NaBH 4 in EtOH all failed. [24] After considerable experimentation, reduction was successfully carried out using Raney-Ni in CH 2 Cl 2 / MeOH to give the tetraamine 1e in 79 % yield.…”

Anion Recognition and Templation in Coordination Chemistry

“…For example, Beer has reported extensive studies on the anion binding properties of substituted metallocenes (mainly ferrocene and cobaltocenium). [11][12][13][14] Figure 2. amide and urea groups) for optimal interaction with the guest; in addition, the electrochemical properties of the metallocenes can be successfully employed as a read-out for the detection of the specific anionic guest.…”