Structure of neohesperidin dihydrochalcone β-cyclodextrin inclusion complex:: NMR, MS, and X-ray spectroscopic investigation

The inclusion complex between the semisynthetic sweetener neohesperidin dihydrochalcone (1) and beta-cyclodextrin (beta CD) has been investigated in solution, in the gas phase and in the solid state. In aqueous solution they form a 1:1 complex having a K-binding of 1.6 x 10(3) M-1 at 315 K. The nuclear Overhauser effects show that the terminal isovanillin ring of 1 is included in the hydrophobic cavity of beta CD from the narrower rim of the truncated cone. The peak at m/z 1747 corresponding to the supramolecular entity [beta CD + 1 + H](+) was detected by MS-FAB measurements. The fragmentation pattern of 1 is different in the presence and in the absence of beta CD, suggesting that the disaccharide moiety of 1 and the external polar surface of the host are tightly associated. In the solid state evidence of the formation of the beta CD/1 complex is obtained from the X-ray powder diffractograms which show diffraction peaks differing in position and intensity from those of native guest 1 and host beta CD.