Supramolecular host−guest interactions of dibenzoylmethanatoboron difluoride with β-cyclodextrin
By D.S. Ionov, G.A. Yurasik, I.V. Ionova, V.A. Sazhnikov, A.A. Safonov, Yu.N. Kononevich, M.V. Alfimov
The complexation of dibenzoylmethanatoboron difluoride (DBMBF2) with β-cyclodextrin (β-CD) was studied in a water/acetone (99:1, v/v) mixture using electronic absorption, steady-state and time-resolved fluorescence spectroscopy as well as the time-resolved fluorescence anisotropy method. The introduction of β-CD to the water/acetone mixture enhanced the solubility of DBMBF2, indicating the formation of a DBMBF2/β-CD complex. Analysis of the fluorescence intensity of DBMBF2 solutions as a function of β-CD concentration revealed a 1:1 binding stoichiometry with a binding constant of 275 M−1. The interaction of DBMBF2 with β-CD results in a reduced fluorescence quantum yield, a shorter fluorescent lifetime, and an increased rotational correlation time. Upon evaporation of the solvent from the solution containing the DBMBF2/β-CD complex, a transparent film is formed, exhibiting a fluorescence spectrum similar to DBMBF2 solutions. The complexation reduced the stability of DBMBF2 to hydrolysis. DFT-based quantum-chemical calculations were used to model the structure of the supramolecular DBMBF2/β–CD complexes.
