1,3-Phenyl linked urea-based receptors for anions and the facile cyclization to imidazolidinedione

Amino acid-based molecules containing a bis-urea moiety have been synthesized and demonstrated for their anion binding affinities. Compound 1c binds phosphate and sulfate with binding constants of 3.6 × 103 M−1 and 4.3 × 103 M−1, respectively. These molecules undergo proton transfer upon treatment with fluoride, resulting in the formation of imidazolidinediones. The crystal structure of one such diimidazolidinedione displays self-assembly through nonconventional hydrogen bonding interactions.