Reversible encapsulation of a nitrate guest via hydrogen-bonded self-assembled capsule formation by a flexible tripodal receptor in polar solvent through dynamic self-assembly

Reversible formation of a self-assembled capsule by dimerization of two units of discrete and highly flexible tripodal receptors through multiple hydrogen bonds in polar solvents is reported. The structural scaffold responsible for the capsule formation was prepared by in situ nitration reaction of the N-terminal aromatic ring of the tripodal receptor. The studies show that the nitro group at the ortho position of the N-terminal aromatic ring is mandatory for hydrogen bonded capsule formation and the mode of hydrogen bonding depends upon the electronic nature of the N-terminal aromatic ring. The present approach has been utilized for reversible encapsulation of a weakly coordinating and hydrophilic nitrate anion through a dynamic self-assembly process.