Electrochemical recognition of anions by 1,1′-N,N′-ferrocenoylbisamino acid esters

Voltammetric Anion Sensors based on Redox‐active Ferrocene‐bearing Macrocyclic Amides

“…This is due to the interaction of oxidized ferrocenium compounds with F – , and the [Fc + –F – ] species formed in the anode scan is more difficult to be reduced in the reverse scan. This is a typical EC mechanistic response , …”

“…In their CV curves, the adsorption of the ion pairs [Fc + –H 2 PO 4 – ] onto the electrode surface was found, as evidenced by the appearance of a significant sharp negative stripping peak in the CV curve of [ L1‐L2 +H 2 PO 4 – ]. This is due to the electrical reduction of the desorption ion pairs adsorbed on the electrode surface in the oxidation step . It also leads to the loss of reversibility of the Fc/Fc + wave.…”

Anion-Binding-Induced Electrochemical Signal Transduction in Ferrocenylimidazolium: Combined Electrochemical Experimental and Theoretical Investigation

“…It is interesting that the E 1/2 values of these receptors actually reflect the distribution of the electrostatic repulsion between ferrocenium and the methyl imidazolium cation. In acetonitrile, it is known that each methyl substitute can negatively shift E 1/2 of ferrocene by about 50 mV [18,20], and further addition of the –CH 2 – subunit to the alkyl chain may shift the potential by a value between −5 mV and −10 mV. Based on the potential shift induced by the electron-withdrawing effect of the methyl imidazolium cation subunits, one can estimate that the ∆ E 1/2 values of these ferrocene-based receptors should be about 324 mV, 217 mV, 53 mV, and 42 mV (vs. Fc/Fc + ) for n = 0, 1, 3, and 4, respectively.…”

“…Receptor molecules with a ferrocene center are widely applied for electrochemical recognition and sensing, largely due to the reversible electro-oxidation of ferrocene to a ferrocenium ion that can exert strong electrostatic interactions [9,16,17,18,19,20]. On the other hand, anion binding by a host molecule is usually achieved or assisted via hydrogen bonding (H-bonding) with the H-donating amide or urea groups, [8,9,21,22,23,24], or H-accepting moieties, such as amine, pyridine, or bipyridine in the host molecules [8,9,21,22,23,24,25].…”

Syntheses, Structure and Electrochemical Anion Recognition of 5-Ferrocenylisophthalicdiacyl Hydrazones

“…The addition of Cl − and H 2 PO 4 − led to flattening of the reduction waves, typical of an EC mechanistic response, such a phenomenon is not abnormal. 24,[29][30] This clearly demonstrates the fact that the Cl − and H 2 PO 4 − anions interact with the oxidised ferrocenium compound. It is reported that unfunctionalised ferrocene displays no electrochemical response to the presence of Cl − anions, 31,32 which indicates the importance of the tweezers in helping to bind the anions and generate the electrochemical response, rather than simple ion-pairing interactions alone being responsible.…”