At the same time, due to complexation process, the –NH (H b )
proton of hydrazide undergoes an upfield shift from d 9.477 ppm
to d 9.019 ppm because the anionic species induces an upfield
chemical shift through diamagnetic shielding. Again noticeable
upfield chemical shifts are also shown in the case of protons of
benzene as well as in naphthalene rings of receptor L which are induced due to complexation after the addition of 5 equivalents of
acetate which is shown in NMR titration curves (Fig. 7).