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[摘要]：Four fanlike org. compds., 1-ethoxybenzene (EOB), 1-butoxybenzene (BOB), 1-dodecyloxybenzene (DOB), and 1-(dodecyloxy)-2-methoxybenzene (DOMB), were chosen as guests, and b-cyclodextrin (b-CD) and its two derivs., mono(2-O-2-methyl)-b-CD and mono(2-O-2-hydroxypropyl)-b-CD, were chosen as hosts. Energy changes involved in host-guest inclusion processes were clearly obtained by applying semiempirical PM3 calcns. According to this, probable structures of the host-guest inclusion complexes were proposed. The inclusion systems in aq. soln. were investigated by UV-vis spectroscopy and NMR (1H NMR) titrn., and the formation consts. (K) of the inclusion complexes were detd. using the Benesi-Hildebrand equation. Moreover, two solid inclusion complexes of b-CD with EOB and DOB were prepd. and characterized by Fourier transform IR spectra, X-ray powder diffraction, 1H NMR, electrospray ionization mass spectrometry, and thermogravimetric analyses. Results showed that the host-guest stoichiometries in the inclusion complexes were all 1:1 both in solid state and in aq. soln. As for the same host, the values of K increased in the order EOB < BOB < DOB, in strong assocn. with the fan handle in the fanlike mols.; that is to say, the K values increased with increasing carbon chain length of substituent on benzene ring. In addn., the K values of DOMB complexes were larger than those of DOB complexes for the same CD, indicating that the introduction of an extra o-methoxyl group on DOB further stabilized the CD inclusion complexes. The decompn. activation energies of EOB-b-CD and DOB-b-CD were very similar but significantly larger than that of free b-CD. |
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