FT-Raman Spectra of 2-, 3-, and 4-Chlorostyrene Molecules Included in Cyclodextrins

FT-Raman spectra of 2-, 3-, and 4-chlorostyrene included in-cyclodextrin (CD),glycerol ether -CD, -CD,sulfated -CD, andglycerol ether -CD were recorded.In the inclusion complexes, the area of the vinyl(C=C) band decreased remarkably, whereasthe area of the phenyl (C=C) band increasedcompared to those of liquid 2-, 3-, and 4-chlorostyrene,respectively. From the results, the inclusion structures of2-, 3-, and 4-chlorostyrene were discussed.     

水溶液中环糊精包结物的包结常数的测定方法

环糊精（CD）是由6，7，8个葡萄糖基构成的环状化合物，分别叫做α、β、γ-CD，它们具有“外亲水，内疏水”的独特性质，可以与多种物质形成包结物，而改变物质的特性，因而被广泛应用于各行各业中，在以往研究的基础上，总结了多种测定环糊精包结常数的方法，以便能更好地研究并开发利用具有极大潜力的环糊精。     

Complexation of Ketoconazole by Native and Modified Cyclodextrins

Complexation of ketoconazole (KET), a broad-spectrum antifungal drug, with β- and γ-cyclodextrins (CDs), heptakis (2,6-di-O-methyl)-β-CD (2,6-DM-β-CD), heptakis (2,3,6-tri-O-methyl)-β-CD (TM-β-CD), 2-hydroxypropyl-β-CD (2HP-β-CD) and carboxymethyl-β-CD (CM-β-CD) was studied. The stability constants were determined by the solubility method at pH = 6 and for 2,6-DM-β-CD and CM-β-CD at pH = 5. At pH = 6, the stability constants increased in the order: TM-β-D < γ-CD < 2HP-β-CD < β-CD < CM-β-CD < 2,6-DM-β-CD. At pH = 5, due to the increased ionization of KET, the stability constant with CM-β-CD increased and with 2,6-DM-β-CD decreased. For complexes of KET with 2HP-β-CD and 2,6-DM-β-CD, the thermodynamic parameters of complexation were determined from the temperature dependence of the corresponding stability constants. For β–γ and TM-β-CD complexes, calculations using HyperChem 6 software by the Amber force field were carried out to gain some insight into the host–guest geometry.     

Spectroscopic Study of the Inclusion Complexes of Phenylbutazone and Oxyphenbutazone with Cyclodextrins in Polar Reaction Media

The formation of inclusion complexes of -, -, hydroxypropyl-- (HP--) and -cyclodextrins with phenylbutazone and oxyphenbutazone has been studied in aqueous buffer solution (pH 7.5 and 0.1 mol dm^-3 NaCl), dimethylsulfoxide, and 25, 50 and 75% dimethylsulfoxide/water mixtures. These complexation reactions have been followed by UV electronic absorption spectroscopy. In addition, 1D and 2D ¹H NMR spectra were recorded to obtain structural information about the inclusion complexes formed in solution; 136 binding constant values were determined at five different temperatures (288, 293, 298, 303 and 310 K) from the electronic absorption data and, from these H_binding and S_binding values were obtained. At the studied cyclodextrin and guest concentration ranges, 1 : 1 inclusion complexes were detected. Only in three cases were 1 : 2 complexes detected, those of phenylbutazone and oxyphenbutazone with -cyclodextrin in aqueous, and oxyphenbutazone with hydroxypropyl--cyclodextrin in 75% dimethylsulfoxide/water solutions.     

Fluorescent Vesicular Particles Assembled by Inclusion Complexes Between Cyclodextrins and BPB

Vesicular particles based on inclusion complexes between BPB and γ-HB-β-CDs were prepared and characterized for the first time. The morphologies and sizes were confirmed by transmission electron microscopy (TEM), scanning electron microscope (SEM), and dynamic light scattering (DLS). Particularly, these vesicular particles exhibiting clearly fluorescent dots observed by laser confocal scanning microscopy (LCSM) could be alternative candidates as fluorescent probes and labels being applied to cellular staining, labeling, bio-mimicking and drug delivery. The ultraviolet, fluorescence, and nuclear magnetic resonance (NMR) measurements confirmed the existence of stable 1:1 BPB-γ-HB-β-CD complexes in the system. The vesicular particles were assumed to be constructed by orderly self-aggregates of these inclusion complexes.     

Vibrational (FT-IR and FT-Raman) and NMR studies on selected metal (Ca, Mn, Zn) complexes with ortho-, meta-, and para-iodobenzoic acids

The vibrational (FT-IR and FT-Raman) and NMR (¹H and ¹³C) spectra of Ca, Mn, and Zn complexes with ortho-, meta-, and para-iodobenzoic acids have been studied. The solid state samples of all complexes have been measured within the range 4000–400 cm⁻¹, while water solutions of ortho-iodobenzoates within the range 4000–800 cm⁻¹. Based on previous experimental data and normal mode calculations for simpler complexes the assignment of bands observed in vibrational spectra of studied compounds has been done. Some significant differences in vibrational structure (frequency and intensity of selected bands) have been observed and discussed. The effect of metal on ring vibrations and carboxylic anion stretching and deformation has been investigated. Also, influence of iodine substitution on the aromatic ring and carboxylic anion, depending on iodine ring position, has been discussed. In case of soluble compounds, wavenumbers of characteristic bands of water solution samples have been compared with wavenumbers of corresponding bands of solid state samples.     

基于环糊精包结络合作用的大分子自组装

本文综述了基于环糊精包结络合作用的大分子自组装的研究进展,包括：（1) 线型、梳型、多臂星型或超支化聚合物与环糊精或其二聚体自组装形成多聚轮烷（分子项链）、多聚准轮烷、双多聚（准）轮烷、分子管、双分子管、超分子凝胶及其应用;（2）桥联环糊精与桥联客体分子自组装制备线型或超支化超分子聚合物;（3）温度、pH值、光及客体分子刺激响应智能体系; （4) 通过亲水性的环糊精线型均聚物与含金刚烷的疏水性聚合物之间的包结络合作用来制备高分子胶束及其空心球等。     

Melatonin/Cyclodextrin Inclusion Complexes: A Review

Melatonin (MLT) is involved in many functions of the human body, mainly in sleeping-related disorders. It also has anti-oxidant potential and has been proven very effective in the treatment of seasonal affective disorders (SAD), which afflict some people during short winter days. Melatonin has been implicated in a range of other conditions, including Parkinson’s disease, Alzheimer’s and other neurological conditions, and in certain cancers. Its poor solubility in water leads to an insufficient absorption that led scientists to investigate MLT inclusion in cyclodextrins (CDs), as inclusion of drugs in CDs is a way of increasing the solubility of many lipophilic moieties with poor water solubility. The aim of this review is to gather all the key findings on MLT/CD complexes. The literature appraisal concluded that MLT inclusion leads to a 1:1 complex with the majority of CDs and increases the solubility of the hormone. The interactions of MLT with CDs can be studied by a variety of techniques, such as NMR, FT-IR, XRD and DCS. More importantly, the in vivo experiments showed an increase in the uptake of MLT when included in a CD.     

Fast Atom Bombardment Mass Spectroscopic Investigation of Inclusion Complexes of Cyclodextrins with 4-Nitrophenol and Benzoic Acid

Mixtures of -, -, and -cyclodextrins and 4-nitrophenol (or benzoic acid) were investigated by means of fast atom bombardment mass spectroscopy. In the gas phase, inclusion complexes of -, , and -cyclodextrins with 4-nitrophenolate and benzoate, which have a 1 : 1 cyclodextrin–guest stoichiometry, were observed in negative-ion mode. In addition, guest anions, clusters of two and three guest molecules, and guest–matrix complexes were observed.     

Complex Formation between Polyisoprene and Cyclodextrins

Summary: Polyisoprenes were found to form inclusion complexes with cyclodextrins with high selectivity to give crystalline compounds. β‐Cyclodextrin formed complexes only with polyisoprene of low molecular weight, whereas γ‐cyclodextrin formed complexes with polyisoprenes of high molecular weight. α‐Cyclodextrin did not form complexes with polyisoprene of any molecular weight. The yields of γ‐cyclodextrin complexes increased with increasing molecular weights of the polyisoprenes and reached a maximum of around several thousands, and then decreased.

Theoretical depiction of the complex formed between polyisoprene and γ‐CD, as determined by molecular modelling studies. The PIP chain is shown penetrating the γ‐CD cavity, which, in turn, accommodates one to 1.5 monomer units of PIP.     

Host–Guest Interactions of Risperidone with Natural and Modified Cyclodextrins: Phase Solubility, Thermodynamics and Molecular Modeling Studies

The solubility of risperidone (Risp) in aqueous buffered cyclodextrin (CD) solution was investigated for α-, β-, γ- and HP-β-CD. The effects of pH, ionic strength and temperature on complex stability were also explored. Neutral Risp tends to form higher order complexes (1:2) with both β- and HP-β-CD, but only 1:1 type complexes with α-, and γ-CD. The tendency of Risp to complex with cyclodextrins is in the order β-CD > HP-β-CD > γ-CD > α-CD. The 1:1 complex formation constant of Risp/HP-β-CD increases with increasing ionic strength in an opposite trend to the inherent solubility (S ₀) of Risp, thus indicating significant hydrophobic effect. The hydrophobic effect contributes to the extent of 72% towards neutral Risp/HP-β-CD complex stability, while specific interactions contribute only 4.7 kJ/mol. Thermodynamic studies showed that 1:1 Risp/HP-β-CD complex formation is driven by a favorable enthalpy change (ΔH ⁰=−31.2 kJ/mol, ΔS ⁰=−7 J/mol.K) while the 1:2 complex is largely driven by entropy changes (ΔH ⁰=−5.0 kJ/mol, ΔS ⁰=42 J/mol.K). Complex stability was found to vary with pH, with a higher formation constant for neutral Risp. Molecular mechanical computations using MM (atomic charges and bond dipole algorithms) and Amber force fields, which were carried out to explore possible sites of interactions between Risp and CDs and to rationalize complex stoichiometry, produced similar results concerning optimal inclusion complex geometries and stoichiometries.     

Stereoselective Complex Formation between Polybutadiene and Cyclodextrins in Bulk

Polybutadienes (PBs) are found to form inclusion complexes with cyclodextrins (CDs) stereoselectively to give crystalline compounds in bulk. These complexes have been isolated and characterized by means of ¹H NMR and ¹³C CP/MAS NMR spectroscopy, and X‐ray diffraction. Although α‐CD did not form inclusion complexes with any kinds of PBs in aqueous solutions, α‐CD did form inclusion complexes with PBs having 1,4‐cis‐ and 1,4‐trans‐butadiene units in bulk by heating at 100 °C. On the other hand, PB having 79% of a 1,2‐structure did not form inclusion complexes with α‐CD. The yield of the inclusion complexes increases with an increase in the content of the 1,4‐cis‐structure of PB and decreases with the molecular weights of the PBs.

     

Physicochemical Properties and Complex Formation Abilities of Large-Ring Cyclodextrins

Large-ring cyclodextrins (LR-CD) are cyclic -1,4-glucanscomposed of nine to more than several hundred glucopyranose units. The firstdefinitive evidence for the existence of LR-CD with a degree of polymerization between 9and 13 was reported in 1965. That LR-CD study did not reveal anything that attracted attention. LR-CD with a degree of polymerization between 9 and 31 were isolated andcharacterized during the past decade, and so began to attract considerable attention. This mini-review summarizes the findings of LR-CD with regard to the potentialfor host-guest interactions and corresponding applications.     

Binary Systems of Nifedipine And Various Cyclodextrins in The Solid State. Thermal,FTIR, XRD studies

Nifedipine complexes with β-cyclodextrin (β-CD), γ-cyclodextrin (γ-CD), 2-hydroxypropyl-β-cyclodextrin (2HP-β-CD), randomly methylated-β-cyclodextrin (RM-β-CD) and heptakis(2,6-O-dimethyl)-β-cyclodextrin (DM-β-CD) have been prepared by both kneading and heating methods and their behaviour studied by differential scanning calorimetry (DSC), diffuse reflectance mid-infrared spectroscopy (FTIR) and X-ray diffractometry (XRD). DSC revealed the nifedipine melting endotherm with onset at approximately 171°C for the kneaded mixtures with β-CD, γ-CD and 2HP-β-CD, thus confirming the presence of nifedipine in the crystalline state, while some decrease in crystallinity was observed in the DM-β-CD kneaded mixture. With RM-β-CD, however, broadening and shifting of the nifedipine endotherm and reduction in its intensity suggested that the kneading could have produced an amorphous inclusion complex. These differing extents of interaction of nifedipine with the cyclodextrins were confirmed by FTIR and XRD studies. This revised version was published online in August 2006 with corrections to the Cover Date.     

A Spectroscopic and Molecular Modelling Study of the Nature of the Association Complexes of Nile Red with Cyclodextrins

The polarity-sensitive fluorescent dye Nile Red forms association complexes with various cyclodextrins in aqueous solution. The formation of such association complexes has a significant effect on the Nile Red fluorescence, with the largest effect being observed in -cyclodextrin solution. When -cyclodextrin is used to increase the Nile Red concentration in solution, the absorption spectrum shows a large blue shift indicating the formation of an inclusion complex, but surprisingly the Nile Red fluorescence is strongly suppressed. A proposed explanation for this observation involves the formation of 1:2 host:guest complexes, in which the Nile Red guests are included as relatively non-fluorescent dimers. When the solutions were prepared by adding -cyclodextrinto a near-saturated aqueous solution of Nile Red (so that 1:1 or 2:1 complexation shouldbe favoured), significant fluorescence enhancement was observed. Analysis of thefluorescence enhancement as a function of host concentration indicated the formationof 2:1 host:guest complexes in these solutions. However, electrospray mass spectroscopic studies show no evidence for the formation of any such inclusion complexes. Furthermore, molecular modelling shows that the formation of a complex involving full insertion of Nile Red in the -cyclodextrin cavity is not stable, and will quickly eject the Nile Red guest molecule. These modelling results suggest that an association complex involving capping (via the association of Nile Red parallel to the cavity opening, or by partial insertion into the cavity) of the -cyclodextrin cavity by one or two Nile Red molecules is much more likely.     

环糊精在聚合反应中的应用

环糊精分子结构上的特点使其在诸多领域有广泛的应用,其中环糊精在聚合反应中的应用正引起广泛关注,已逐渐成为高分子科学研究的重要领域。环糊精不但可以用于形成超分子聚合物,而且可以用于单体分子的聚合反应中。环糊精在聚合反应中不但可以担当单体、引发剂、模板,同时,还起到增溶、分子伴侣、反应活性调控、改变聚合物性质等作用。本文综述了近年来环糊精及其衍生物在聚合物合成过程中应用的研究进展,着重介绍了环糊精在合成聚合物中所起到的不同作用、应用原理等方面的研究成果,并对此领域的未来发展做了展望。     

FTIR, FT-Raman spectra and ab initio DFT vibrational analysis of 2,4-dichloro-6-nitrophenol

The FTIR and FT-Raman spectra of 2,4-dichloro-6-nitrophenol (2,4-DC6NP) has been recorded in the region 4000-400 cm(-1) and 3500-100 cm(-1), respectively. The optimized geometry, frequency and intensity of the vibrational bands of (2,4-DC6NP) were obtained by the ab initio and DFT levels of theory with complete relaxation in the potential energy surface using 6-31G(d,p) and 6-311+G(d,p) basis sets. The harmonic vibrational frequencies were calculated and the scaled values have been compared with experimental FTIR and FT-Raman spectra. The observed and the calculated frequencies are found to be in good agreement. The experimental spectra also coincide satisfactorily with those of theoretically constructed bar type spectrograms.     

Combinations of Cyclodextrins with Synthetic and Natural Compounds

Host–guest compounds formed by cyclodextrins with synthetic and natural compounds are reviewed with regard to their properties, characterisation (using experimental and computational methods) and applications.     

The Interaction of Piroxicam with Neutral (HP-β-CD) and Anionically Charged (SBE-β-CD) β-cyclodextrin

The interaction of piroxicam (PX) with sulfobutylether-β-cyclodextrin (SBE-β-CD) was studied by fluorescence spectroscopy and compared with that of hydroxypropyl-β-cyclodextrin (HP-β-CD). The stability constants (K) values for the PX-CDs complexes were obtained by steady-state fluorescence measurements. Inclusion conditions including concentrations of the two cyclodextrins and pH values were investigated for the complex formation in detail. The results suggested that the interaction of PX with charged CD (SBE-β-CD) is much stronger than that with uncharged CD (HP-β-CD) at any pH studied, in terms of a synergetic effect of hydrophobic and additional electrostatic interactions.