The binding constants (log Kass ) of small synthetic receptor molecules based on indolocarbazole, carbazole, indole, urea and some others, as well as their combinations were measured for small carboxylate anions of different basicity, hydrophilicity and steric demands, that is, trimethylacetate, acetate, benzoate and lactate, in 0.5 % H2 O/[D6 ]DMSO by using the relative NMR-based measurement method. As a result, four separate binding affinity scales (ladders) including thirty-eight receptors were obtained with the scales anchored to indolocarbazole. The results indicate that the binding strength is largely, but not fully, determined by the strength of the primary hydrogen-bonding interaction. The latter in turn is largely determined by the basicity of the anion. The higher is the basicity of the anion the stronger in general is the binding, leading to the approximate order of increasing binding strength, lactate

Carboxylates are attractive target analytes in supramolecular analytical chemistry. 22 acyclic synthetic receptors with different numbers and geometric arrangements of hydrogen‐bond donors (HBD) and hydrophobic moieties have been applied to experimentally study selective binding of 11 carboxylate anions of widely differing basicity, hydrophobicity and steric demand, which resulted in 242 accurately determined binding constants. It was found that besides the basicity of the anions, structural and steric factors of anions and receptors influence the binding. Several interesting cases are pinpointed and analysed. The ability of selected receptors to discriminate between anions according to structural features (hydrophilicity, substitution at α‐carbon, etc.) is demonstrated. The present results give insight into carboxylate anion binding and make an important step towards systematic development of receptors with useful selectivity patterns and thereby to the practical use of receptor series in sensor arrays for carboxylate fingerprinting in mixtures.

The hydrogen-bond (HB) donicity of various HB donors, expressed as standard Gibbs free energy of HB formation with chloride ion, was studied experimentally in dimethyl sulfoxide (DMSO) and computationally in DMSO and the gas phase. Acidity and HB donicity data in the gas phase and DMSO have been obtained for 77 HB donors from different compound families. Applicability of two computational methods (SMD and COSMO-RS) for calculation of solvation contribution to reaction free energy in DMSO was evaluated and discussed. The quality of calculated Gibbs free energies of solvation was assessed using the correlation between HB strengths in solvent and in the gas phase. The investigation of the relationships between HB donicity and Brønsted acidity showed that in the gas phase the correlation is good, and within structurally uniform compound groups both acidity and donicity are described well by substituent constants. The same correlation in DMSO is less distinct. Bidentate HB donors are characterized by higher HB donicity than could be expected from their acidity in both media, and therefore, these HB donors have an important advantage in anion binding applications, e.g., in catalysis.

The construction and study of solid‐contact acetate‐selective electrodes is described using a 1,3‐bis(carbazolyl)urea derivative as a neutral hydrogen‐bonding ionophore and poly(3,4‐ethylenedioxythiophene) as the solid contact. It was shown recently that this ionophore binds acetate (logKass=4.98) that is used as primary ion in this study. The electrodes show linearity over the activity range of 10−4.50–10−1.10 with a sub‐Nernstian slope of −51.3 mV per decade and a detection limit of 10−5.00. The anion‐selectivity pattern of these electrodes deviates markedly from the Hofmeister pattern. When adding ionophore to the membrane the logarithm of the selectivity coefficient (logK) for SCN− decreased from 6.5 to 1.2, logK for I− decreased from 5.7 to 0.9, logK for NO3− decreased from 4.3 to 0.6 and logK for Br− decreased from 3.3 to 0.1. The selectivity coefficients of hydrophilic anions such as Cl−, F−, HPO42−, and SO42− are significantly lower than in case of the ionophore‐free membrane. It was discovered that the constructed electrodes are also relatively selective to bicarbonate. This work is an important step towards the further development of solid‐contact anion‐selective electrodes.

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