Efficient “antenna effect” in the complex of (+) catechin and Tb(III) lodged inside the nano-cavity of β-cyclodextrin

A complex of Tb(III) with (+) catechin (C) has been profitably encapsulated within the β-CD cavity at physiological pH = 6.9 in aqueous medium. The ternary system exhibits a remarkable ‘antenna effect’ compared to the complex of Tb(III) with C. Time resolved measurement of Tb(III) emission in H2O and in D2O directly proves the protection of Tb(III) from OH oscillator within the cavity. The rotational correlation time of bound C obtained from time resolved anisotropy further confirms the motional restriction of C in the ternary system providing enhanced energy transfer efficiency. The simple system may help improve designing imaging technique in aqueous medium.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► We encapsulate successfully Tb(III) complex within the nano cavity of β-CD. ► We choose a ligand which has the ability to bind Tb(III) as well as to penetrate in the interior of the cavity. ► A remarkable enhance ‘antenna effect’ is observed due to effective shielding of Tb(III) and restricted motion of the ligand within the cavity. ► The ternary system may help design an improved imaging technique in aqueous medium.