A Comparative Study on the Binding Behaviors of β-Cyclodextrin and Its Two Derivatives to Four Fanlike Organic Guests

Abstract

Four fanlike organic compounds, 1-ethoxybenzene (EOB), 1-butoxybenzene (BOB), 1-dodecyloxybenzene (DOB), and 1-(dodecyloxy)-2-methoxybenzene (DOMB), were chosen as guests, and beta-cyclodextrin (beta-CD) and its two derivatives, mono(2-O-2-methyl)-beta-CD and mono(2-O-2-hydroxy-propyl)-beta-CD, were chosen as hosts. Energy changes involved in host-guest inclusion processes were clearly obtained by applying semiempirical PM3 calculations. According to this, probable structures of the host-guest inclusion complexes were proposed. The inclusion systems in aqueous solution were investigated by UV-vis spectroscopy and nuclear magnetic resonance ((1)H NMR) titration, and the formation constants (K) of the inclusion complexes were determined using the Benesi-Hildebrand equation. Moreover, two solid inclusion complexes of beta-CD with EOB and DOB were prepared and characterized by Fourier transform infrared spectra, X-ray powder diffraction, (1)H 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 aqueous solution. As for the same host, the values of K increased in the order EOB < BOB < DOB, in strong association with the fan handle in the fanlike molecules; that is to say, the K values increased with increasing carbon chain length of substituent on benzene ring. In addition, 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 decomposition activation energies of EOB-beta-CD and DOB-beta-CD were very similar but significantly larger than that of free beta-CD.

Inclusion Complex of Novel Curcumin Analogue CDF and β-Cyclodextrin (1:2) and Its Enhanced In Vivo Anticancer Activity Against Pancreatic Cancer

“…These results confirmed the intercalation of CDF in β-cyclodextrin and formation of CDF-β-cyclodextrin inclusion complex. The small differences in the FTIR peaks of β-cyclodextrin and CDF before and after inclusion complex formation suggests that there are no chemical bonds formed between CDF and β-cyclodextrin (25). …”

Experimental and computational study of the inclusion complexes of β-cyclodextrin with the chemical warfare agent soman (GD) and commonly used simulants

“…Although the magnitudes of binding energies determined by this method are oen unrealistic, they generally predict the correct rank order of complex formation. 32,33 To introduce a further level of complexity it was assumed that GD would be solvated so a simulation of GD surrounded by 55 water molecules (to approximate a molar solution) was initiated to determine if there were any signicant hydrogen bonds formed between the CWA and surrounding solvent. All non-hydrogen bonding water molecules were removed prior to a second geometry optimisation iteration by PM6.…”

Preparation, characterization and molecular modeling studies of the inclusion complex of Caffeine with Beta-cyclodextrin

“…They are able to form inclusion complexes with a wide variety of guest molecules [14][15]. The guest molecule has been the most favorable changes in the physicochemical properties, like stability, dissolution rate, solubility, and bioavailability due to inclusion complex formation between the drug molecules with CDs [16][17][18].…”