The sensing property of the receptor was also investigated in
acetonitrile/water (9/1, v/v). As expected, in the presence of water,
the sensing behavior of the receptor is slightly diminished (Fig. 5).
This may be due to the interaction of the guest with water.
In the case of pure acetonitrile media the absorbance of the
receptor L (1 ? 10 ?5 M) increases fivefold on the addition of
5 equiv of tetrabutylammonium acetate (2 ? 10 ?4 M) while in
acetonitrile–water mixture the fourfold increase occurs by the
addition of 10 equiv of acetate in same experimental conditions
that is there is a loss of some sensitivity in acetonitrile-water media. This is why we choose only acetonitrile for the titration purpose
for proper sensing of the receptor