A water-soluble acyclic phane receptor recognizing 2,3-trans-gallate-type catechins.

To recognize gallate-type catechins in aqueous solution, two water-soluble acyclic phane receptors containing three aromatic rings were synthesized. The binding of these receptors to eight catechin analogues was investigated with (1)H NMR spectroscopy. The stoichiometric ratios of the complexes between the receptors and the catechins were 1:1 in every case. The binding abilities were estimated by (1)H NMR titration. The meta-substituted receptor showed excellent binding ability for the 2,3-trans-gallate-type catechins. This study revealed that a simple acyclic phane receptor can distinguish differences in the structures of the catechin analogues.