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刘育, Yu Liu, *, †, Li Li, Zhi Fan, Heng-Yi Zhang, Xue Wu, ‡, Xu-Dong Guan, † and Shuang-Xi Liu†
Nano Lett., Vol. 2, No.4, 2002,-0001,():
-1年11月30日
A novel supramolecular assembly has been fabricated by the inclusion complexation between organo-selenium bridged bis(β-cyclodextrin)s 2 and calix[4]arene derivative 3 in water-acetonitrile (1:1) mixture solution and characterized by fluorescence, 2D NMR, TEM, SEM, and STM images, showing the nanometer structural wire-shaped aggregates.
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刘育, Yu Liu, * En-Cui Yang, Ying-Wei Yang, Heng-Yi Zhang, Zhi Fan, Fei Ding, and Rui Cao
J. Org. Chem. 2004, 69, 173-180,-0001,():
-1年11月30日
The complex stability constants (KS) and thermodynamic parameters (△G°, △H°, and T△S°) for 1:1 inclusion complexation of β-cyclodextrin (β-CD) derivatives, 6-O-phenyl-β-CD (2) 6-O-(4-formylphenyl)-β-CD (3), 6-O-(4-nitrophenyl)-β-CD (4), 6-O-(4-bromophenyl)-β-CD (5), 6-O-(4-chlorophenyl)]-β-CD (6), and 6-O-(4-hydroxybenzoyl)-β-CD (7) with representative guest molecules, cyclic alcohols (cyclopentanol, cyclohexanol, cycloheptanol, cyclooctanol), (±)-borneol, and (±)-camphor, have been determined by means of titration microcalorimetry in an aqueous phosphate buffer solution (pH=7.20) at 298.15K. The results obtained indicate that the introduction to β-CD of an aromatic ring bearing different substituent groups significantly enhances the molecular binding ability and moderately alters the chiral discrimination ability for the guests examined here, displaying the highest enantioselectivity of up to 4.01 for the inclusion complexation of 6 with (±)-camphor. The enhanced molecular/chiral discrimination ability caused by derivatization is attributed solely to increased positive entropy changes due to the expanding hydrophobic interaction and desolvation effects. The binding modes of host-guest interactions derived from ROESY spectroscopy data show that the resulting complex of 4 and (+)-borneol possesses better induced-fit interaction as compared to (-)-borneol, which is responsible for the enhanced molecular/chiral recognition ability.
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刘育, Yu Liu, *, †, Chang-Cheng You, Heng-Yi Zhang, Shi-Zhao Kang, ‡, Chuan-Feng Zhu, ‡ and Chen Wang‡
Nano Lett., Vol. 1, No.11, 2001,-0001,():
-1年11月30日
A novel supramolecular assembly, bis(molecular tube)s composed of complexes of organoselenium-bridged β-cyclodextrins and platinum(Ⅳ) ion, have been fabricated via the pseudorotaxane with poly(propylene glycol) and characterized by 1H NMR, TEM, and AFM images, etc.
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刘育, Yu Liu, * Li Li, Heng-Yi Zhang, and Yun Song
J. Org. Chem. 2003, 68, 527-536,-0001,():
-1年11月30日
To investigate quantitatively the cooperative binding ability of β-cyclodextrin dimers, a series ofbridged bis(β-cyclodextrin)s with 2,2'-diselenobis(benzoyl) spacer connected by different lengths of oligo(ethylenediamine)s (2-5) and their platinum(Ⅳ) complexes (6-9) have been synthesized and their inclusion complexation behavior with selected substrates, such as Acridine Red, Neutral Red, Brilliant Green, Rhodamine B, ammonium 8-anilino-1-naphthalenesulfonate, and 6-p-toluidino-2-naphthalenesulfonic acid, were investigated by means of ultraviolet, fluorescence, fluorescence lifetime, circular dichroism, and 2D-NMR spectroscopy. The spectral titrations have been performed in aqueous phosphate buffer solution (pH 7.20) at 25°C to give the complex stability constants (KS) and Gibbs free energy changes (-△G°) for the inclusion complexation of hosts 2-9 with organic dyes and other thermodynamic parameters (△H°and T△S°) for the inclusion complexation of 2-5 with fluorescent dyes ANS and TNS. The results obtained indicate that β-cyclodextrin dimers 2-5 can coordinate with one or two platinum(Ⅳ) ions to form 1:1 or 1:2 stoichiometry metallobridged bis(β-cyclodextrin)s. As compared with parent β-cyclodextrin (1) and bis(β-cyclodextrin)s 2-5, metallobridged bis(β-cyclodextrin)s 6-9 can further switch the original molecular binding ability through the coordinating metal to orientate two β-cyclodextrin cavities and an additional binding site upon the inclusion complexation with model substrates, giving the enhanced binding constants KS for both ANS and TNS. The tether length between two cyclodextrin units plays a crucial role in the molecular recognition with guest dyes. The binding constants for TNS decrease linearly with an increase in the tether length of dimeric β-cyclodextrins. The Gibbs free energy change (-△G°) for the unit increment per ethylene is 0.32kJ•mol-1 for TNS. Thermodynamically, the higher complex stabilities of both ANS and TNS upon the inclusion complexation with 2-5 are mainly contributed to the favorable enthalpic gain (-△H°) by the cooperative binding of one guest molecule in the closely located two β-cyclodextrin cavities as compared with parent β-cyclodextrin. The molecular binding ability and selectivity of organic dyes by hosts 1-9 are discussed from the viewpoints of the multiple recognition mechanism and the size/shape-fitting relationship between host and guest.
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刘育, Yu Liu, * Chang-Cheng You, and Bin Li[a]
,-0001,():
-1年11月30日
Four bridged bis(b-cyclodextrin) s tethered by different lengths of oligo(ethylenediamine)s have been synthesized and their inclusion complexation behavior with selected substrates elucidated by circular dichroism spectroscopy and fluorescence decay. In order to study their binding ability quantitatively, inclusion complexation stability constants with four dye guests, that is, brilliant green (BG), methyl orange (MO), ammonium 8-anilino-1-naphthalenesulfonic acid (ANS), and sodium 6-(p-toluidino)-2-naphthalenesulfonate (TNS), have been determined in aqueous solution at 25 8C with spectrophotometric, spectropolarimetric, or spectrofluorometric titrations. The results obtained indicate that the two tethered cyclodextrin units might cooperatively bind to a guest, and the molecular binding ability toward model substrates, especially linear guests such as TNS and MO, could be extended. The tether length plays a crucial role in the molecular recognition, the binding constants for ANS and TNS decrease linearly with an increase in the tether length of dimeric cyclodextrin. The Gibbs free energy changes (
cyclodextrins
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