Calix[3]amide-based anion receptors: high affinity for fluoride ions and a twisted binding model
摘要:
Tris-phenylurea-substituted calix[3]amides (3a, 3b) and tris-phenylthiourea-substituted calix[3]amides (4a, 4b) were synthesised by the reaction of amine with isocyanates and thioisocyanate, respectively. Single crystal X-ray analysis revealed that the cyclic trimers adopt a syn conformation with all of the urea groups on the same side. The binding affinities of these compounds towards anions were measured using 1H NMR titrations in DMF-d7, DMSO-d6 or CDCl3. Each receptor was observed to bind halogen anions in a 1:1 stoichiometry, exclusively through hydrogen bonding, and the anion selectivity was in the order F- Cl->> Br- I-. DFT calculations revealed that the fluoride anion is anchored in the centre of the six N-H hydrogen atoms of 3a through H center dot center dot center dot F interactions.
Calix[3]amide-based anion receptors: high affinity for fluoride ions and a twisted binding model
摘要:
Tris-phenylurea-substituted calix[3]amides (3a, 3b) and tris-phenylthiourea-substituted calix[3]amides (4a, 4b) were synthesised by the reaction of amine with isocyanates and thioisocyanate, respectively. Single crystal X-ray analysis revealed that the cyclic trimers adopt a syn conformation with all of the urea groups on the same side. The binding affinities of these compounds towards anions were measured using 1H NMR titrations in DMF-d7, DMSO-d6 or CDCl3. Each receptor was observed to bind halogen anions in a 1:1 stoichiometry, exclusively through hydrogen bonding, and the anion selectivity was in the order F- Cl->> Br- I-. DFT calculations revealed that the fluoride anion is anchored in the centre of the six N-H hydrogen atoms of 3a through H center dot center dot center dot F interactions.
Tris-phenylurea-substituted calix[3]amides (3a, 3b) and tris-phenylthiourea-substituted calix[3]amides (4a, 4b) were synthesised by the reaction of amine with isocyanates and thioisocyanate, respectively. Single crystal X-ray analysis revealed that the cyclic trimers adopt a syn conformation with all of the urea groups on the same side. The binding affinities of these compounds towards anions were measured using 1H NMR titrations in DMF-d7, DMSO-d6 or CDCl3. Each receptor was observed to bind halogen anions in a 1:1 stoichiometry, exclusively through hydrogen bonding, and the anion selectivity was in the order F- Cl->> Br- I-. DFT calculations revealed that the fluoride anion is anchored in the centre of the six N-H hydrogen atoms of 3a through H center dot center dot center dot F interactions.