The structural analysis of the inclusion complex of β-cyclodextrin with m-nitrophenoxyacetic acid

The inclusion complex of β-cyclodextrin with m-nitrophenoxyacetic acid was studied by single crystal X-ray diffraction,2D NMR spectroscopy and semi-empirical methods AMI.The crystallographic study shows that two β-cyclodextrins are held together by hydrogen bonds to form head-to-head dimers.The disordered guest molecule adjusts itself to attain the most stable accommodation into the cavity in which the nitro group is located at the dimer interface while the carboxyl group is buried in the primary hydroxyl groups of β-cyclodextrin.The guest inside the cavity is disordered over two sites and exhibits mobility.Moreover,2D NMR spectroscopy and theoretical study show the same inclusion behavior.In comparison to the inclusion complex of β-cyclodextrin with p-nitrophenoxyacetic acid,the host-guest stoichiometries are different,i.e.,2:1 for m-nitrophenoxyacetic acid and 1:1 for p-nitrophenoxyacetic acid,while the inclusion orientation and the packing pattern of the host are similar in both complexes.     

Crystal structure of β-cyclodextrin-4-chlorobenzoic acid complex:Unusual C-Cl…π interaction between 4-chlorobenzoic acids in β-cyclodextrin dimer

The inclusion complex ofβ-cyclodextrin（β-CD） with 4-chlorobenzoic acid was synthesized and its crystal structure was determined by single crystal X-ray diffraction under cryogenic condition.The complex contains twoβ-CDs,two 4-chlorobenzoic acids and twenty-nine water molecules in the asymmetric unit,and can be formulated as 2(C₄₂H₇₀O₃₅)·2（C₇H₅O₂Cl）·29（H₂O）.In the crystal lattice,twoβ-CDs form a face-to-face dimer jointed together through hydrogen bonding between the secondary hydroxyl groups ofβ-CDs.Two 4-chlorobenzoic acid molecules which contact by C-Cl…πinteractions are included in theβ-CD dimer cavity.Theβ-CD dimers are arranged in brickwork-like pattern along the crystallographic a-axis.The effect of guest molecule length on the inclusion geometry was discussed by comparative study of someβ-CD complexes containing similar guests.     

Comparative Study on the Inclusion Interaction between meso-Tetrakis（4-N-ethylpyridiniurmyl） porphyrin and β-Cyclodextrin Derivatives

The interaction of β-cyclodextrin (β-CD) and the modified cyclodextrins, hydroxy propyl-β-cyclodextrin (HP-β-CD), sulfobutylether-β-cyclodextrin (SBE-β-CD) and synthesized meso-tetrakis(4-N-ethylpyridiniurmyl)porphyrin (TEPyP) in aqueous solution has been studied by spectroscopic methods systematically. A significant change in fluorescence and absorption properties has been observed in the presence of β-CD, HP-β-CD and SBE-β-CD. The stoichiometry and formation constants have been determined by the steady-state fluorescence technique. The results showed that the β-CD derivatives were prior to the native β-CD and the hydrogen bonding and static electric forces played important roles in the formation of the inclusion complexes. The conformation was further confirmed by NMR spectroscopy.     

A Large Conformational Change of a Bridged β－Cyciodextrin Dimer in Aqueous Solution

A novel bridged β-CD dimer in which two β-cyclodextrius were linked by a naphthalene at positions 2 and 7 has been synthesized. ^1H and ^13CNMR measurements showed that a large change in the conformation of the dimer occurred in aqueous solution. The dimer interacted with methyl and ethyl orange to form stable inclusion complexes v/a “induced fit“ mechanism.     

Using PVP/SDS Complex as a Probe to Study the Inclusion Complex of β-cyclodextrin with SDS in Aqueous Solution

PVP/SDS complex was applied as a probe to study the interaction between β-cyclodextrin （β-CD） and sodium dodecyl sulfate （SDS） in aqueous solution. It has been found that a critical concentration, namely cs, exists in the relative viscosity of solution containing PVP/SDS complex versus β-CD concentration plot. As the β-CD concentration is less than cs, the relative viscosity of solution decreases sharply by adding β-CD into solution successively. On the other hand, as the β-CD concentration is greater than cs, the relative viscosity of solution increases gradually by adding β-CD into solution. The decrease of the relative viscosity of solution containing PVP/SDS in the presence of β-CD is just due to the inclusion complex of β-CD with the guest molecule SDS. And, this inclusion interaction takes down SDS from the PVP chains in solution. The ratio of the host molecule β-CD to the guest molecule SDS can be calculated from Cs. In our experiment the inclusion ratio of β-CD to SDS is 1/1. The further experimental results indicate that cs is associated with SDS but free from PVP in PVP/SDS complex. However, the inclusion ratio of β-CD to SDS has proved to be independent of either SDS or PVP in PVP/SDS complex.     

Study on the inclusion behavior and solid inclusion complex of 5-amino-6-methyl-2-benzimidazolone with cyclodextrins

The inclusion behaviors of three native or modified CDs including p-CD,2-hydroxypropyl-β-CD(2-Hp-β-CD) and 2,6-dimethyl-β-CD(Me-β-CD) toward 5-amino-6-methyl-2-benzimidazolone(AMBI) were comparatively investigated by NMR and fluorescence titration in combination with IR spectra,X-ray diffractometry and scanning electron microphotographs.The experimental results jointly demonstrated that the phenyl ring of AMBI entered into the cavity of the CDs and located close to the narrow rims accompanied by the formation of the 1:1 inclusion complex with large stability constant in aqueous solution.The introduction of the hydroxypropyl unit to the host improved the solubility,ultimately effecting an obvious promoting in the fluorescence intensity and the stability constant     

Study on the Supramolecular Interaction of β-Cyclodextrin with Gemfibrozil by Spectrofluorimetry and Its Analytical Application

The supramolecular interaction of gemfibrozil with β-cyclodextrin （β-CD） was studied by spectrofluorimetry. The mechanism of the inclusion was discussed by spectrofluoremetry, infrared spectrum and ^1H NMR spectrum. The results showed that a 1 ： 1 （β-CD ： gemfibrozil） complex was formed with an apparent association constant of 3.844 × 10^3 L·mol^-1. Based on the enhancement of the fluorescent intensity of gemfibrozil, a spectrofluorimetric method for the determination of gemfibrozil in bulk aqueous solution in the presence of β-CD was developed. The linear range was 3.30 ng·mL^- 1 -6.00 ug·mL^-1 with the detection limit of 0.980 ng·mL^-1. There was no interference from the excipients normally used in tablet composition and the serum main compositions. The proposed method was then successfully applied to the determination of gemfibrozil in capsules and serum.     

PREPARATION AND CHARACTERIZATION OF INCLUSION COMPLEXES OF TWO-ARM LINEAR AND FOUR-ARM STAR-SHAPED POLY（ε-CAPROLACTONE）S WITH α-CYCLODEXTRIN

Both four-ann star-shaped poly（ε-caprolactone） （4sPCL） and two-ann linear PCL （2LPCL） were synthesized and their inclusion complexation with α-cyclodextrin （α-CD） were studied. The inclusion complexes （ICs） formed between the PCL polymers and α-CD were characterized by ^1H-NMR, DSC, TGA, WAXD, and FT-1R, respectively. Both branch ann number and molecular weight of the PCL polymers have apparent effect on the stoichiometry （CL：CD, mol：mol） of these ICs. All these analytical results indicate that the branch arms of the PCL polymers are incorporated into the hydrophobic α-CD cavities and their original crystalline properties are completely suppressed. Moreover, the inclusion complexation between two-ann linear or four-ann star-shaped PCL polymers and α-CD not only enhances the thermal stability of the guest PCL polymers but also improves that of α-CD.     

Investigation of Inclusion Complexes Between α-Cyclodextrin and Ferrocene by ESI-MSn and Cyclic Voltammetry

The inclusion complexes of α-cyclodextrin (α-CD) and FcCO2 (CH2)18(FcSH) and their self-as-sembled monolayers (SAMs) on gold surface were investigated by electrospray tandem ionization mass spectrometry (ESI-MS″) and cyclic voltammetry, respectively. The interfacial electrochemical response of the SAMs is related to the way in which the inclusion complexes formed.     

环糊精与两种有机物的包合物的不同光解特性

The effectiveness of the solubilization and photodegradation of β-cyclodextrin （β-CD） and hydroxypropyl-β- cyclodextrin （HPCD） on two hydrophobic organic compounds （HOC） of methyl parathion and pentachlorophenol was investigated. The results indicate that the solubilization or photodegradation of two HOC were influenced by complexing with β-CD or HPCD. The solubility of pentachlorophenol （PCP） was increased linearly with β-CD concentration. The solubility of methyl parathion （MPT） was increased with the increase of β-CD concentration initially, however, as the β-CD concentration was enhanced above 3 g/L, the solubility was decreased with increase of β-CD concentration. The solubilities of two HOC were increased linearly with the increase of HPCD concentration. Although the photodegradation of MPT was improved, the photodegradation of PCP was restrained by complexation of HOC with β-CD or HPCD. In a word, the effectiveness of photodegradation or solubilization of HPCD was more significant than that of β-CD. One potential application of such a method was the in situ remediation of hydrophobic organic pollutants in contaminated soil and groundwater or industrial waste streams.     

Quantitative ROESY analysis of computational models: structural studies of citalopram and β‐cyclodextrin complexes by 1H‐NMR and computational methods

Complexation of racemic citalopram with β‐cyclodextrin (β‐CD) in aqueous medium was investigated to determine atom‐accurate structure of the inclusion complexes. ¹H‐NMR chemical shift change data of β‐CD cavity protons in the presence of citalopram confirmed the formation of 1 : 1 inclusion complexes. ROESY spectrum confirmed the presence of aromatic ring in the β‐CD cavity but whether one of the two or both rings was not clear. Molecular mechanics and molecular dynamic calculations showed the entry of fluoro‐ring from wider side of β‐CD cavity as the most favored mode of inclusion. Minimum energy computational models were analyzed for their accuracy in atomic coordinates by comparison of calculated and experimental intermolecular ROESY peak intensities, which were not found in agreement. Several least energy computational models were refined and analyzed till calculated and experimental intensities were compatible. The results demonstrate that computational models of CD complexes need to be analyzed for atom‐accuracy and quantitative ROESY analysis is a promising method. Moreover, the study also validates that the quantitative use of ROESY is feasible even with longer mixing times if peak intensity ratios instead of absolute intensities are used. Copyright © 2015 John Wiley & Sons, Ltd.     

Fluorescence Sensing and Selective Binding of a Novel 4,4′‐Sulfonyldianiline‐Bridged Bis(β‐cyclodextrin) for Bile Salts

A novel 4,4′‐sulfonyldianiline‐bridged bis(β‐cyclodextrin (CD)) 2 was synthesized, and its complex stability constants (K_s) for the 1 : 1 inclusion complexation with bile salts, i.e., cholate (CA), deoxycholate (DCA), glycocholate (GCA), and taurocholate (TCA) have been determined in phosphate buffer (pH 7.2) at 25° by fluorescence spectroscopy. The result indicated that 2 can act as efficient fluorescent sensor and display remarkable fluorescence enhancement upon addition of optically inert bile salts. Structures of the inclusion complexes between bile salts and 2 were elucidated by 2D‐NMR experiments, indicating that the anionic tail group and the D ring of bile salts penetrate into one CD cavity of 2 from the wide opening deeply, while the phenyl moiety of the CD linker is partially self‐included in the other CD cavity to form a host–linker–guest binding mode. As compared with native β‐CD 1 upon complexation with bile salts, bis(β‐CD) 2 enhances the binding ability and molecular selectivity. Typically, 2 gives the highest K_s value of 26200 M ^?1 for the complexation with CA, which may be ascribed to the simultaneous contributions of hydrophobic, H‐bond, and electrostatic interactions. These phenomena are discussed from the viewpoints of multiple recognition and induce‐fit interactions between host and guest.     

NMR spectra and structures of oridonin derivatives complexes with β‐cyclodextrin

Complexations between three oridonin derivatives and β‐cyclodextrin (βCD) were studied by nuclear magnetic resonance (NMR) method. Job's plots for complexes were depicted by ¹H NMR spectra chemical shifts, which proved the 1:1 stoichiometry inclusion complex formation between each derivative and βCD. Two‐dimensional rotating frame overhauser effect spectroscopy (2D ROESY) support the above conclusion and also proved that ring A of each oridonin derivative deeply enters into hydrophobic cavity from the wider rim and the other parts are outside the cavity. Apparent formation constants (K_a) of complexes between three oridonin derivatives and two CDs are calculated according to Scott's equation. Copyright © 2011 John Wiley & Sons, Ltd.     

固相β-环糊精包结物诱导7-羟基-2-甲氧基-2-甲基色满的不对称合成

研究了室温下间苯二酚和甲基乙烯基酮分别与β-环糊精（ β-CD）形成包结物后的几种不同固相反应,结果表明包结物A（间苯二酚/β-CD）与包结物B（甲基乙烯基酮/β-CD）反应能够很好地得到目的产物,产率及ee值分别为82.8%和78.4%;间苯二酚与包结物B反应仅得到低光学活性产物（ee值为19.5%）;包结物A与甲基乙烯基酮反应却没有得到手性目的产物。以熔点、X-粉末衍射、固相核磁碳谱及ROESY多种方法对所形成的包结物进行了表征,包结物中主客体的比例（1：1）通过¹H NMR (400 MHz)得以确定,文章对固相环加成反应的机制也进行了初步探讨。     

High Resolution NMR Spectroscopic Study of Complexation of Hydroxyzine Hydrochloride with β‐Cyclodextrin in Aqueous Solution

Hydroxyzine hydrochloride forms two 1:1 inclusion complexes with β‐cyclodextrin in aqueous solution as confirmed by the ¹H NMR titration and ROESY studies. One complex is formed by the deep penetration of the chlorophenyl ring from the wider rim side, while the mode of entry of the phenyl ring into the β‐CD cavity is not clear. The stoichiometry and overall association constant of the complexes have been determined by the treatment of ¹H NMR shift data. Some chiral discrimination by the host between the two enantiomers of hydroxyzine hydrochloride is also indicated.     

Structural Studies for Specific Binding Capacity of β‐Cyclodextrin with Ibuprofen

Ibuprofen (Ibu) and β‐cyclodextrin (βCD) and its derivative (hydroxypropyl‐β‐cyclodextrin, HPβCD) complexes spatial geometry information were studyed. Firstly, phase solubility experiment was carried out for S‐(+)‐ibuprofen (SIbu) and cyclodextrins complex. The apparent stability constant (Kc) for 1:1 complexes are 1065 M‐1 (βCD) and 1476 M‐1 (HPβCD) respectively. Secondly, ¹H NMR and two‐dimensional rotating‐frame overhauser effect spectroscopy (2D ROESY) were used for binding study, and confirmed that benzene ring of Ibu is deeply included into the cavity and racemic Ibu (RSIbu) can be discriminated by βCD or HPβCD. Finally, docking model was given by theoretical investigation. The model with ‐4.77 kcal/mol binding energy matches experimental structure.     

一种经(E)-α-碘代烯基砜的钯催化交叉偶联反应立体选择合成(1Z,3E)-2-芳砜基取代的1,3-二烯的新方法

（E）-α-Stannylvinyl phenyl（or p-tolyl）sulfones underwent an iododestannylation reaction to afford （E）-α-iodovinyl phenyl（or p-tolyl）sulfones 1, which reacted with （E）-alkenylzirconium（IV） complexes 2 produced in situ by hydrozirconation of terminal alkynes in the presence of a Pd（PPh3）4 catalyst to afford stereoselectively （1Z,3E）-2- phenyl（or p-tolyl）sulfonyl-substituted 1,3-dienes 3 in good yields.     

NMR spectroscopic characterization of inclusion complexes comprising cyclodextrins and gallated catechins in aqueous solution: cavity size dependency

The structure of inclusion complexes of γ‐cyclodextrin (γ‐CD), (–)‐gallocatechin gallate (GCg), and (–)‐epigallocatechin gallate (EGCg) in D₂O was investigated using several NMR techniques. GCg formed a 1:1 inclusion complex with γ‐CD in which the A and C rings of GCg were inserted deep at the head of the A ring into the γ‐CD cavity from the wide secondary hydroxyl group side. In the 1:1 inclusion complex with GCg and γ‐CD, the GCg moiety maintained a conformation in which the B and B′ rings of GCg took both pseudoequatorial positions with respect to the C ring. The structure of the inclusion complex of GCg and γ‐CD obtained from NMR experiments supported well that determined from PM6 semiempirical SCF MO calculations. However, ¹H NMR experiments suggested that EGCg did not form any inclusion complex with γ‐CD in D₂O. The marked difference between GCg and EGCg in inclusion behavior toward γ‐CD may be explained in terms of the stabilization energy calculated with the PM6 method. Copyright © 2008 John Wiley & Sons, Ltd.     

Thiosemicarbazonates of Ruthenium(II): Crystal Structures of [Bis(triphenylphosphine)][bis(N‐phenyl‐pyridine‐2‐carbaldehyde Thiosemicarbazonato)]ruthenium(II) and [Bis(diphenylphosphino)butane][bis(salicylaldehyde Thiosemicarbazonato)]ruthenium(II)

Reaction of RuCl₂(PPh₃)₃ with N‐Phenyl‐pyridine‐2‐carbaldehyde thiosemicarbazone (C₅H₄N–C²(H)=N³‐N²H–C¹(=S)N¹HC₆H₅, Hpytsc‐NPh) in presence of Et₃N base led to loss of ‐N²H‐proton and yielded the complex [Ru(pytsc‐NPh)₂(Ph₃P)₂] ( 1 ). Similar reactions of precursor RuCl₂[(p‐tolyl)₃P]₃ with a series of thiosemicarbazone ligands, viz. pyridine‐2‐carbaldehyde thiosemicarbazone (Hpytsc), salicylaldehyde thiosemicarbazone (H₂stsc), and benzaldehyde thiosemicarbazone (Hbtsc), have yielded the complexes, [Ru(pytsc)₂{(p‐tolyl)₃P}₂] ( 2 ), [Ru(Hstsc)₂{(p‐tolyl)₃P}]₂ ( 3 ), and [Ru(btsc)₂{(p‐tolyl)₃P}₂] ( 4 ), respectively. The reactions of precursor Ru₂Cl₄(dppb)₃ {dppb = Ph₂P–(CH₂)₄–PPh₂} with H₂stsc, Hbtsc, furan‐2‐carbaldehyde thiosemicarbazone (Hftsc) and thiophene‐2‐carbaldehyde thiosemicarbazone (Httsc) have formed complexes of the composition, [Ru(Hstsc)₂(dppb)] ( 5 ), [Ru(btsc)₂(dppb)] ( 6 ), [Ru(ftsc)₂(dppb)] ( 7 ), and [Ru(ttsc)₂(dppb)] ( 8 ). The complexes have been characterized by analytical data, IR, NMR (¹H, ³¹P) spectroscopy and X‐ray crystallography ( 1 and 5 ). The proton NMR confirmed loss of –N²H– proton in all the compounds, and ³¹P NMR spectra reveal the presence of equivalent phosphorus atoms in the complexes. In all the compounds, thiosemicarbazone ligands coordinate to the Ru^II atom via hydrazinic nitrogen (N²) and sulfur atoms. The arrangement around each metal atom is distorted octahedral with cis:cis:trans P, P:N, N:S, S dispositions of donor atoms.     

β-环糊精与有机胺之间包合作用的理论与实验研究

通过实验和理论计算方法研究了β-环糊精(CD)与乙二胺1及它的三个类似物: 二乙烯三胺2、三乙胺3和乙二胺四乙酸4之间的包合作用. 利用旋光法确定了β-CD与客体分子形成1:1型主–客体包合物, 在298.2 K下测定了包合物在水中的稳定常数(K). 采用半经验PM3方法考察了β-CD与短链脂肪胺1~7、环状脂肪胺8~11以及芳香胺12~13的分子间结合能力, 报道了β-CD与这些客体分子间的包合络合过程并讨论了这些包合体系之间的包合差异性. 变形能和水合能对包合体系的相互作用能的贡献均相当小. β-CD包合物的稳定性取决于主、客体分子之间的尺寸匹配. 对于β-CD与客体1~4形成的包合物而言, 旋光法测定的包合物的K值的顺序与PM3计算得到的包合物络合能绝对值的排序有很好的一致性.