Asymmetric urea, thiourea and squaramide receptors as minimal-anion binding motifs

Bobbie Mcvey, Joanna Rumble, Charis Nathan, Ian Gass, Mark Sambrook, Peter Cragg

Research output: Contribution to journalArticlepeer-review


Asymmetric minimal receptors based on 4-nitrophenylurea, 1, and 4-nitrophenylthiourea, 2, were shown to bind a range of anions and are deprotonated by both fluoride and hydroxide to give a colorimetric response. A 4-trifluoromethylphenylurea receptor, 3, was deprotonated by fluoride but not hydroxide but was not discernible by the naked eye. Deprotonation of 1 by fluoride ultimately resulted in the formation of its bicarbonate complex as determined by X-ray crystallography in agreement with DFT calculations. Fluorescence spectroscopy revealed that emission of 2 reaches a maximum at two equivalents of anions except for fluoride where it continues to increase with increasing addition of TBAF allowing 2 to give a fluoride-specific response.
Original languageEnglish
Pages (from-to)208-222
Number of pages15
JournalSupramolecular Chemistry
Issue number5-6
Publication statusPublished - 28 Jan 2024


  • Urea
  • thiourea
  • anion binding
  • DFT
  • crystal structure


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