70900-82-2Relevant academic research and scientific papers
Inclusion effects of cyclomaltohexa- and heptaose (α- and β-cyclodextrins) on the acidities of several phenol derivatives
Hamai, Sanyo,Satoh, Noriko
, p. 229 - 237 (2007/10/03)
By means of spectrophotometry, equilibrium constants for the formation of 1:1 inclusion complexes of cyclomaltohexaose (α-cyclodextrin, α-CD) or cyclomaltoheptaose (β-CD) in aqueous solutions have been evaluated for neutral and anionic species of 3-cyanophenol, 4-cyanophenol, 3-nitrophenol, 4-nitrophenol, 4-bromophenol, and 4-methoxyphenol. Using the equilibrium constants of the neutral and anionic species, pK(a) values have been determined for the phenols bound to the α- and β-CD cavities. These phenols, which are accommodated in the α-CD cavity, have been found to be stronger acids than the free, uncomplexed ones, except for 4-methoxyphenol. On the other hand, 4-cyanophenol, 3-nitrophenol, and 4-methoxyphenol bound to the β-CD cavity are weaker acids than the uncomplexed ones, although,3-cyanophenol, 3-nitrophenol, and 3-bromophenol bound to β-CD show the same trend as those bound to α-CD. The different influences of α- and β-CDs on the pK(a) values are likely due to the difference in the magnitudes of the induced dipole moments of the guest caused by α- and β-CDs; depending on the magnitude of the induced dipole moment, the inclusion complexes are stabilized through the dipole-dipole interaction between the host and guest.
A CROSS-POLARISATION-MAGIC-ANGLE SPINNING 13C-N.M.R. STUDY OF SOLID-STATE CYCLOAMYLOSE INCLUSION-COMPLEXES WITH SUBSTITUTED BENZENES: 13C-CHEMICAL SHIFTS AND MOLECULAR DYNAMICS OF THE INCLUDED GUESTS
Inoue, Yoshio,Okuda, Takehiro,Kuan, Fu-Hua,Chujo, Riichiro
, p. 9 - 20 (2007/10/02)
The chemical shifts and line-shapes of cross-polarisation-magic-angle sample spinning 13C-n.m.r. resonances have been analysed for p-nitrophenol, p-hydroxybenzoic acid, benzoic acid, and m-nitrophenol in the solid state and likewise for inclusion complexes with host cyclomalto-hexaose and -heptaose.The trends of the chemical-shift displacements induced by complexation with the cycloamyloses in the solid state did not fully correspond with those for solutions.The line-shapes showed evidence of the rotational motion of the benzene compounds in the cavity of cyclomaltohexaose, but not in that of cyclomaltoheptaose.
