Observation and Interpretation of Anomalous Inorganic Anion Binding with α- and β-Cyclodextrins in Aqueous Media

Godı́nez, Luis A.; Schulze-fiehn, Brita G.; Patel, Sonal M.; Criss, Cecil M.; Evanseck, Jeffrey D.; Kaifer, Ángel E.

doi:10.1080/10610279608233964

Cited by 24 publications

(16 citation statements)

References 24 publications

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“…Also, three of the thermodynamic parameters defined in Scheme 1 are known and, therefore, the value of K ox can then be calculated for compounds 1 and 3 using Equation 1. As can be seen by inspection of the resulting values in Table 2, K ox is fairly small for both systems, a fact that is not only consistent with the observed one -wave shift behavior, but also with the previously reported values obtained for similar b-CD complexes by means of other experimental techniques [25].…”

supporting

confidence: 88%

Analysis of the Voltammetric Response of Electroactive Guests in the Presence of Non‐Electroactive Hosts at Moderate Concentrations

Mendoza¹,

Castaño²,

Meas³

et al. 2004

Electroanalysis

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In this work, we present a method to analyze the voltammetric response of reversible redox systems involving molecules that, bearing m non-interactive electroactive sites, can undergo fast complexation equilibria with host molecules present at concentrations of the same order of magnitude as those of the electroactive guest. The approach focuses on systems for which the relative values of the binding constants for the oxidized and reduced forms of the guest result in the displacement of the voltammetric response of the electroactive molecule as the concentration of the host is increased in the electrolytic solution. This behavior is commonly known as "one wave shift behavior". Based on a series of assumptions, the method allows calculation of all the thermodynamic parameters that describe the electrochemical and complexation equilibria of a given host-guest system. The main strength of the suggested method, however, relies on the fact that it only requires cyclic voltammetry data and that it can be used for systems in which large concentrations of the host can not be employed either due to important changes of the ionic strength or to solubility problems. Although the accuracy of the obtained information is limited by the quality of the data provided by the technique, and by the assumptions employed, it certainly represents an excellent starting point for subsequent refinement either using digital simulations or an independent experimental technique.

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confidence: 88%

Analysis of the Voltammetric Response of Electroactive Guests in the Presence of Non‐Electroactive Hosts at Moderate Concentrations

Mendoza¹,

Castaño²,

Meas³

et al. 2004

Electroanalysis

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“…One of the key requirements for the recognition of hydrated anions is undoubtedly a large, well-defined binding pocket, the circumambient nature of which allows for multi-point recognition. − But what are the specifics of such pockets? How many waters of hydration are easily removed from an anion, and is there a preferred hydration geometry for each anion type?…”

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confidence: 99%

Binding Hydrated Anions with Hydrophobic Pockets

et al. 2015

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Using a combination of Isothermal Titration Calorimetry and quantum and MD calculations, we demonstrate that relatively soft anions have an affinity for hydrophobic concavity. The results are consistent with the anions remaining partially hydrated upon binding, and suggest a novel strategy for anion recognition. Graphical abstractThe challenges associated with anion recognition are well known. 1 They have a range of geometries, may be pH sensitive, and are larger than the equivalent isoelectronic cations and have a lower charge to radius ratio. This diffuse nature means that across all the classes of functional groups utilized to bring about recognition, 1-2 those involving Coulombic attraction and hydrogen bonding have proven to be the most popular. This is particularly true for anion recognition in aqueous solution, where these strategies have been utilized to counter the strong interactions between the anion and its hydration shell. 3 Thus most of the reported hosts for anions that function in pure/buffered water are cationic. 4 Moving away from this strategy is the idea of utilizing halogen bonds for recognition; 5 an approach that takes advantage of the orthogonality between the requirements for forming halogen bonds, and those for forming hydrogen bonds; if the latter is not utilize, competition with water is less important.An alternative strategy is not to compete with the waters of hydration but to bind the anion with its solvation shell. Although a wide range of ditopic receptors have been synthesized and studied, 6 in general supramolecular chemistry has focused on the recognition of singular species. But why not recognize a hydrated anion rather than a "naked" one? Although this posses many challenges, it sidesteps the energetic requirements of ion desolvation, and has Correspondence to: Steven W. Rick; Bruce C. Gibb. Supporting Information. NMR and ITC titration experiments and details of the quantum and MD simulations. One of the key requirements for the recognition of hydrated anions is undoubtedly a large, well-defined, binding pocket; the circumambient nature of which allows for multi-point recognition. 8,9,10,11 But what are the specifics of such pockets? How many waters of hydration are easily removed from an anion, and is there a preferred hydration geometry for each anion type? Although much has been learned about isolated water clusters 12 and the solvation requirements of ions, 13 what we know of the structural requirements for recognizing hydrated ions is -to our knowledge -limited to the solid state. 14 We recently showed that perchlorate (ClO 4 − ) has an affinity for the hydrophobic pocket of cavitand 1, and that this association is dependent on the nature of other salts. 15 Furthermore, ClO 4 − binding is able to induce Hofmeister effects in the binding of amphiphilic guests to HHS Public Access 1. 16 Here we demonstrate that anion binding to the concavity of 1 is general, use ITC to identify that these complexation events are strongly exothermic and entropically penalized...

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“…However, the concentration of CDP5 had to be increased tenfold (500 g mL −1 ) as the binding of FS to the CDP5 turned out to be inhibited with the standard polymer load. This phenomenon most likely originated from the presence of diverse micro pollutants like phosphates that are prone to interact with the cyclodextrin moieties of the polymer [33,34]. Attempted removals of phosphates by ion-exchange chromatography or precipitation failed to recover a polarization as high as in pure water with a CDP5 concentration of 50 g mL −1 .…”

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confidence: 92%