Synthesis of a water-soluble 2,2'-biphen[4]arene and its efficient complexation and sensitive fluorescence enhancement towards palmatine and berberine.

ABSTRACT: A water-soluble 2,2'-biphen[4]arene (2,2'-CBP4) containing eight carboxylato moieties was synthesized and characterized. Its complexation behavior towards two alkaloids, palmatine (P) and berberine (B), was investigated by means of fluorescence and ¹H NMR spectroscopy in aqueous phosphate buffer solution (pH 7.4). In the presence of 2,2'-CBP4, ¹H NMR signals of P and B displayed very large upfield shifts, indicating the formation of inclusion complexes with strong binding affinities. Fluorescence titration experiments showed that P and B exhibited dramatic fluorescence enhancement of more than 600 times upon complexation with 2,2'-CBP4. Particularly, the fluorescence intensity is strong enough to be readily distinguished by the naked eye. Although the two guests have similar structures, the association constant of B with 2,2'-CBP4 (K_a = (2.29 ± 0.27) × 10⁶ M^-1) is 3.9 times larger than that of P (K_a = (5.87 ± 0.24) × 10⁵ M^-1).

SUBMITTER: Huang X 

PROVIDER: S-EPMC6122385 | biostudies-literature | 2018

REPOSITORIES: biostudies-literature