CC BY-NC-ND 4.0 · Organic Materials 2022; 4(03): 61-72
DOI: 10.1055/a-1896-6890
Supramolecular Chemistry
Original Article

Selective Recognition of Ammonium over Potassium Ion with Acyclic Receptor Molecules Bearing 3,4,5-Trialkylpyrazolyl Groups

Felix Fuhrmann
a   Institut für Organische Chemie, Technische Universität Bergakademie Freiberg, Leipziger Strasse 29, 09599 Freiberg, Germany
,
Wilhelm Seichter
a   Institut für Organische Chemie, Technische Universität Bergakademie Freiberg, Leipziger Strasse 29, 09599 Freiberg, Germany
,
a   Institut für Organische Chemie, Technische Universität Bergakademie Freiberg, Leipziger Strasse 29, 09599 Freiberg, Germany
› Author Affiliations


Abstract

Among the 1,3,5-trisubstituted 2,4,6-triethylbenzenes bearing pyrazolyl groups, the compounds with 3,5-dimethylpyrazolyl moieties were found to be effective receptors for ammonium ions (NH4 +). The current study investigated the extent to which the incorporation of an additional alkyl group in the 4-position of the pyrazole ring affects the binding properties of the new compounds. 1H NMR spectroscopic titrations and investigations using isothermal titration calorimetry revealed that this small structural variation leads to a significant increase in the binding strength towards NH4 + and also improves the binding preference for NH4 + over K+. In addition to the studies in solution, crystalline complexes of the new triethyl- and trimethylbenzene derivatives, bearing 3,4,5-trialkylpyrazolyl groups, with NH4 +PF6 were obtained and analyzed in detail. It is noteworthy that two of the crystal structures discussed in this work are characterized by the presence of two types of ammonium complexes. Studies focusing on the development of new artificial ammonium receptors are motivated, among other things, by the need for more selective ammonium sensors than those based on the natural ionophore nonactin.



Publication History

Received: 08 June 2022

Accepted after revision: 06 July 2022

Accepted Manuscript online:
11 July 2022

Article published online:
11 August 2022

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