Macrocycle conformation and self-inclusion phenomena in octakis(3-O-butanoyl-2,6-di-O-pentyl)-gamma-cyclodextrin (Lipodex E) by NMR spectroscopy and molecular dynamics.
Octakis(3-O-butanoyl-2,6-di-O-pentyl)-gamma-cyclodextrin (Lipodex E) is a lipophilic chiral selector successfully used for the enantioselective gas chromatographic separation of a multitude of racemic analytes. NMR data (13C chemical shifts, 3J(HH), rotating frame NOEs (ROEs)) and molecular dynamics (MD) simulations point out that the macrocycle is distorted with respect to the canonical truncated-cone shape of native cyclodextrins, although C(8) symmetry is retained on the NMR timescale. ROE data and MD trajectories provide evidence for self-inclusion of one 6-O-pentyl pendant chain within the cavity of Lipodex E. The interpretation of long-range and low-intensity ROEs is supported by the calculation of average internuclear distances by using the radial distribution function (RDF) calculated from MD trajectories. MD simulations are eventually used to compare the flexibility of the macrocycle of Lipodex E with that of native gammaCD.
Mele
Andrea
A
Dipartimento di Chimica, Materiali ed Ingegneria Chimica 'G. Natta'-Politecnico di Milano, Via L. Mancinelli 7, I-20131, Milano, Italy. andrea.mele@polimi.it
Raffaini
Giuseppina
G
Ganazzoli
Fabio
F
Juza
Markus
M
Schurig
Volker
V
D003198:Computer Simulation; D003505:Cyclodextrins / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D008968:Molecular Conformation; D015394:Molecular Structure; D013997:Time Factors; D047408:gamma-Cyclodextrins
D003505:Cyclodextrins; D047408:gamma-Cyclodextrins; C113626:octakis(3-O-butanoyl-2,6-di-O-pentyl)cyclodextrin