Crown ether-thiourea conjugates as ion transporters

Abstract

Na⁺, Cl^‒ and K⁺ are the most abundant electrolytes present in biological fluids that are essential to the regulation of pH homeostasis, membrane potential and cell volume in living organisms. Herein, we report synthetic crown ether-thiourea conjugates as a cation/anion symporter, which can transport both Na⁺ and Cl⁻ across lipid bilayers with relatively high transport activity. Surprisingly, the ion transport activities were diminished when high concentrations of K⁺ ions were present outside the vesicles. This unusual behavior resulted from the strong affinity of the transporters for K⁺ ions, which led to predominant partitioning of the transporters as the K⁺ complexes in the aqueous phase preventing the transporter incorporation into the membrane. Synthetic membrane transporters with Na⁺, Cl^‒ and K⁺ transport capabilities may have potential biological and medicinal applications.

Graphical abstract

Keywords

ion transport / thiourea / crown ether / symport

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Acknowledgements

We greatly appreciate the support of this work by the National Natural Science Foundation of China (Grant Nos. 21820102006, 91856118, 21435003 and 21521004), the MOE of China through Program for Changjiang Scholars and Innovative Research Team in University (Grant No. IRT13036), and the Scientific and Technological Plan Project in Xiamen (Grant No. 3502Z20203025).

Electronic Supplementary Material

Supplementary material is available in the online version of this article at https://dx.doi.org/10.1007/s11705-021-2049-7 and is accessible for authorized users.

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