Electrochemical sensing of anions by redox-active receptors built on the ferrocenyl cyclam framework

Electrochemical Anion Sensing: Supramolecular Approaches

“…Almost invariably early voltammetric anion sensors, but also recent examples, are based on N–H hydrogen bond donors. A large variety of such systems, mainly containing amide and urea binding sites, were reported in the 1990s and have been reviewed extensively. , Many of these early systems and the majority of more recent examples in the last two decades, utilize an integrated Fc redox transducer with amine, − amide, − imidazole, − amide/urea macrocycle, , thiourea, amidine, guanidine, , cyclotriveratrylene-amide, calix[4]­pyrrole, calix[4]­arene-amide, , calix[4]­arene-urea, , or calix[4]­arene-amine/imine conjugates (see Figure for examples). Their sensory performance does not significantly deviate from those of earlier systems; most display a progressive cathodic shift of the respective Fc/Fc + redox couple upon anion addition with some displaying a “two-wave” behavior, of which a representative example, as assessed by SWV, is shown in Figure .…”

Viologen-based redox-switchable anion-binding receptors

“…[1][2][3][4] A wide range of synthetic anion receptors have yet been designed in efforts to improve binding strengths, selectivities and signaling processes. [5][6][7][8][9][10] These investigations have demonstrated that efficient transductions of molecular recognition events require the intimate association between binding and signalling moieties into multicomponent architectures. 11 Chromogenic chemosensors are known to be particularly attractive systems allowing low detection limits, but redox analogs conversely require much simpler technologies to simultaneously activate/deactivate and enable recognition processes.…”

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

“…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]. Ammonium- and guanidinium-containing hosts are important examples capable of offering strong electrostatic attractions to anionic guests [19,25,26,27,28]. In addition, receptors containing imidazolium [29,30,31,32,33,34,35,36,37] and triazolium [38,39] are able to recognize anions via a combined strong electrostatic attraction to anions and the (C–H) + ···X − type of H-bonding [25].…”