Consistent Binding Aptitude of Halides and Oxyanions via Cooperative vs. Non‐Cooperative Binding Modes by Neutral Napthyl Bis‐Urea Receptors

Two electron‐rich napthyl ring containing bisurea receptor derived from ortho ( L 1 ) and meta ( L 2 )‐phenylenediamine moiety were designed and synthesized for investigating their anion coordination behavior. L 1 self‐assembled in presence of organic terephthalate anion into a dimeric pseudo‐capsular host‐assembly sealed by tetrabutylammonium counter cation (Complex 1 c ). However, L 2 self‐assembled in 2:4 host‐guest fashions (Complex 2 d ) with H‐bonded dihydrogenphosphate tetrameric anionic guest in the presence of excess n ‐TBA (H 2 PO 4 ). Further, receptor L 1 has been found to self‐assembled into unimolecular cooperative 1:1 complex in presence of spherical Chloride anion (Complex 1 a ) and planar Acetate anion (Complex 1 b ). Moreover, receptor L 2 forms similar kind of non‐capsular host‐guest assembly in presence of spherical halides like Cl − , Br − , and F − . To validate the result obtained in the solid state studies, 1 H‐NMR titration experiments have also been performed using n ‐TBA salts of anions to inspect the solution state anion binding behavior of isomeric receptors L 1 and L 2 .