Triphenylamine-based receptors in selective recognition of dicarboxylic acids.

New triphenylamine-based chemosensors for selective recognition of dicarboxylic acids have been designed and synthesized. They are variants of previously synthesized chemosensors, offering different possibilities for selective recognition of dicarboxylic acids. Theoretical calculations by density functional theory and time dependent density functional theory have been carried out on these as well as on one of the previously reported systems and on complexes formed by the triphenylamine based chemosensors and aliphatic dicarboxylic acids of different chain-lengths. Carboxylic acid binding takes place through charge-neutral pyridyl amide receptor sites with concomitant quenching of fluorescence of the triphenylamine moiety. The theoretical results are consistent with the experimental and correlation is found between the calculated binding energies and the experimental binding constants.