engleski

HSO4¯ sensing based on proton transfer in H-bonding complexes

Aminophenyl-substituted adamantane-dipyrromethane receptors 1 and 2 and aminophenylpyrrole 3 showed a very pronounced and unique UV spectral response with HSO4¯ in aprotic as well as in aqueous media. The fitting of the binding isotherms with HSO4¯ indicated formation of the complexes with the 1:2 (host:anion) stoichiometry. ESI-MS study with mixtures of receptor 3 and TBAHSO4 of different ratio indicated an association of the HSO4¯ and receptor 3, as well as association of the HSO4¯ species into dimers. The unique UV spectral response with HSO4¯ is proposed to be due to proton transfer from HSO4¯ to the amino group of the receptor, which in an aprotic solvent probably takes place in the corresponding H-bonded complexes. The assignations of the spectral changes were corroborated by computation. Moreover, theoretical study indicated that "intra-supramolecular" proton transfer took place whereas presence of the second HSO4¯ was required to enhance the acidity of the first H-bonded anion.

adamantane dipyrromethane receptors ; anion sensing ; HSO4¯sensors ; H-bonded complexes ; proton transfer

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