One-Pot Synthesis and Transmembrane Chloride Transport Properties of C3-Symmetric Benzoxazine Urea.

One-pot synthesis of a C3-symmetric benzoxazine-based tris-urea compound is discussed. 1H NMR titrations indicate a stronger Cl- binding compared that of Br- and I- by the receptor. Effective Cl- transport across liposomal membranes via a Cl-/X- antiport mechanism is confirmed. Theoretical calculation suggests that a few water molecules with N-H, C═O, and the aromatic ring of the receptor create a H-bonded polar cavity where a Cl- is recognized by O-H···Cl- interactions from five bridged water molecules.