Steric inhibition of hydrogen bonding in molecular recognition of dicarboxylic acids: di-topic receptors containing a nitro group designed to behave like monotopic receptors

Five receptors (1–5) including two macrocyclic receptors have been designed and synthesized for the recognition of dicarboxylic acids. The receptors having an NO₂ group show inhibition in hydrogen bonding molecular recognition towards the dicarboxylic acid and this effect becomes more prominent in the case of macrocyclic receptors 4 and 5 in CHCl₃. The binding behavior of these receptors has been studied by UV-vis, fluorescence and 1 : 1 ¹H NMR binding studies.