Uncovering the true mechanism of optical detection of HSO4- in water by Schiff-base receptors--hydrolysis vs. hydrogen bonding.

The mechanism of optical detection of HSO(4)(-) in aqueous medium by Schiff-base receptors has previously been proposed to depend on selective hydrogen-bond interactions. Here, we clearly demonstrate for the first time that the acidic nature of this anion gives rise to hydrolysis of the Schiff base, which leads to the optical changes observed in this family of receptors.