Ortho-phenylenediamine Based Molecular Receptors in Anion Recognition

Abstract

Recognition and sensing of anionic substrates by artificial host is one of the important areas in field of supramolecular chemistry. Among the various anion binding motifs, ortho-phenylenediamine is one of the important hydrogen bonding motif for anions and the receptors based on this motif can differentiate the anions of different topologies. The electronic and steric effects can influence the binding behavior of the ortho-phenylenediamine motif when it remains connected with the other groups (either chromophoric group or the hydrogen bonding group) via urea or thiourea linkages. To date several ortho-phenylenediamine- based urea/amide or urea-amide conjugates have been reported and this mini review highlights the importance of ortho-phenylenediamine based charge-neutral receptors in anion recognition with selected examples.