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 β-cyclodextrin (βCD) 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 × 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 βCD from the narrower rim of the truncated cone. The peak at m / z 1747 corresponding to the supramolecular entity [βCD + 1 + H] + was detected by MS−FAB measurements. The fragmentation pattern of 1 is different in the presence and in the absence of βCD, 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 βCD/ 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 βCD.