Article
Liu et al.
ronment in present of bCD. However discrimination capa-
bility is lower in present of bCD than HPbCD because the
peak of H-j and k of SIbu is only wider but not split.
2D ROESY experimental
CONCLUSIONS
Phase solubility experiment shows that SIbu forms
aqueous soluble 1:1 type complexes with bCD or HPbCD.
HPbCD solution brings solubility increasing higher than
bCD. The values of Kc for 1:1 complex are 1065 M-1 (bCD)
and 1476 M-1 (HPbCD), respectively. The different of Kc
More detail spatial interaction and corresponding
three-dimensional geometry information between host and
guest complex are given by ROESY spectra. The cross
peaks for protons, which the corresponding internuclear
distance is smaller than 3~4 Å, can be observed in 2D
ROESY. Fig. 3 shows the expansion of the ROESY spec-
trum. We do not study the H-b proton of SIbu interaction
with bCD because H-b proton is covered by bCD protons
peaks. Cross peaks between H-e and H-f protons of SIbu
and H-3, 5 and 6 protons of bCD were found, indicating
that aromatic protons of SIbu are deeply included into bCD
cavity. Cross peaks between H-h and i protons of SIbu and
H-3, 5 and 6 protons of bCD were also found, however the
cross peak intensity of H-h is larger than of H-i proton. This
suggests H-i proton is closer to the median line of cavity,
thus far away from H-3, 5 and 6, and H-h is closer to H-3, 5,
and 6. Cross peaks between H-j, k and H-3, 5 and 6 suggest
that methyl group is also inserted into the bCD cavity.
Cross peak between SIbu proton and H-6 suggest that H-e
to k are close to the narrower rim. None cross peak was
found between H-a and H-3, 5, and 6, that suggests H-a
proton is outside bCD cavity and near the wider rim.
Theoretical Investigation
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values suggest the different inclusion process. The H
NMR shows different inclusion structure of SIbu-bCD and
SIbu-HPbCD complexes. 1H NMR also shows H-a and H-e
of RSIbu are split. This means RIbu and SIbu are discrimi-
nated by HPbCD or bCD. 1H NMR and ROESY show aro-
matic nucleus of Ibu is included into bCD cavity, and theo-
retical investigation manifest that SIbu-bCD docking
model with -4.77 kcal/mol binding energy matches experi-
mental structure.
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J. Chin. Chem. Soc. 2012, 59, 000-000