PhD Scientific Days 2026

Pharmaceutical Sciences and Health Technologies 4.

Synthesis of Novel Chloride Ion Recognition Molecules

Name of the presenter

Piros, László

Institute/workplace of the presenter

Department of Organic Chemistry

Authors

Dr. László Piros¹
1: Department of Organic Chemistry

Text of the abstract

Introduction: Urea and similar thiourea moieties are recognized for their capability of anion binding. This property is achieved through hydrogen-bonding interactions, thus acidity is a key factor, which is directly influenced by electronegativity. Partial chloride ion selectivity is present in case of thiocarbamide-containing molecules, it is possible because some anions, like fluoride and bromide ions, moderately deprotonate the bonding site, but chloride exerts no deprotonation, leaving the two hydrogens intact, which is crucial for the anion recognition.
Aims: Synthesis of novel chloride ion recognition molecules containing thiourea derivatives was set as a goal. Reactivity of the different phenyl isothiocyanates used in the reactions was planned to investigate.
Methods: Hence these molecules proved to be thermodynamically relatively unstable in the initial acetonitrile solvent, further trials led to an optimized reaction environment, where acetone or N,N-dimethylformamide (DMF) was used at room temperature for the syntheses. Chloride ion recognition was determined by NMR titration by a different research group of the institution.
Conclusion: Twenty-one novel molecules were synthesized. Phenyl isothiocyanates with electron-withdrawing groups (EWG) underwent faster reactions. In contrast, electron donating groups (EDG) slowed reactions so much down, that DMF was used for reasonable reaction times, but compromised extractability. These properties were reflected in the chloride ion binding ability as well. EWG bearing molecules had a stronger chloride ion recognition tendency compared to EDG containing ones. The type of the amino acid did not significantly affect the binding, its absence made the anion interaction even stronger.
Funding: This research was funded by the Hungarian Research Foundation (OTKA ANN
139484). The financial support of the National Research, Development and Innovation Office
(TKP2021-EGA-31) is acknowledged. Project no. RRF-2.3.1-21-2022-00015 has been implemented with support provided by the European Union.