Abstract A series of mono-or bis-sulfonylthioureas has been synthesized via nucleophilic substitution of potassium sulfonamides and sodium dithiocarbamate in water under mild conditions, and their properties as anion receptors in the absence and presence of K+ have been investigated by 1 H NMR spectroscopy. It was found that calix [4] crown-5 derivative 10 shows much higher selective complexation capability with H2PO4
![N-[Phenylamino(thioxo)methyl]benzenesulfonamide Structure](https://image.chemsrc.com/caspic/443/24539-87-5.png)