Synthesis and Characterization of β‐Cyclodextrin Based Functional Monomers and its Copolymers with N‐isopropylacrylamide

Two novel monovinyl β‐cyclodextrin (β‐CD) monomers are synthesized. Their chemical compositions are characterized by means of element analysis, NMR and FT‐IR spectroscopy. The results show that the synthesis techniques used are convenient and efficient. Using N‐isopropylacrylamide as a comonomer, two novel linear copolymers can also be synthesized.

Synthesis route of monovinyl β‐CD monomers.     

β‐cyclodextrin‐capped palladium nanoparticle‐catalyzed ligand‐free Suzuki and Heck couplings in low‐melting β‐cyclodextrin/NMU mixtures

Low‐melting β‐cyclodextrin/N‐methylurea (NMU) mixture, an efficient catalytic system for ligand‐free Suzuki and Heck couplings in the presence of fresh native β‐CD‐capped Pd⁰ nanoparticles, has been successfully reported. This natural and convenient system can be performed in air and could afford the corresponding cross‐coupled products in good to excellent isolated yields after a simple workup under every low Pd loading (0.05 mol%). Remarkably, the catalytic system can be recycled and reused without loss of catalytic activity. Copyright © 2014 John Wiley & Sons, Ltd.     

Chiral capillary electrophoresis with cationic pyrrolidinium‐β‐cyclodextrin derivatives as chiral selectors

New single‐isomer, cationic β‐cyclodextrins, including mono‐6‐deoxy‐6‐pyrrolidine‐β‐cyclodextrin chloride (pyCDCl), mono‐6‐deoxy‐6‐(N‐methyl‐pyrrolidine)‐β‐cyclodextrin chloride (N‐CH₃‐pyCDCl), mono‐6‐deoxy‐6‐(N‐(2‐hydroxyethyl)‐pyrrolidine)‐β‐cyclodextrin chloride (N‐EtOH‐pyCDCl), mono‐6‐deoxy‐6‐(2‐hydroxymethyl‐pyrrolidine)‐β‐cyclodextrin chloride (2‐MeOH‐pyCDCl) were synthesized and used as chiral selectors in capillary electrophoresis for the enantioseparation of carboxylic and hydroxycarboxylic acids and dansyl amino acids. The unsubstituted pyCDCl exhibited the greatest resolving ability. Most analytes were resolved over a wide range of pH from 6.0 to 9.0 with this chiral selector. In general, increasing pH led to a decrease in resolution. The effective mobilities of all the analytes were found to decrease with increasing CD concentration. The optimal concentration for most carboxylic acids and dansyl amino acid was in the range 5–7.5 mM and >15 mM for hydroxycarboxylic acids. ¹H NMR experiments provided direct evidence of inclusion in the CD cavity.     

X‐ray photoelectron spectroscopic study of Tencel treated with a cationic β‐cyclodextrin derivative

The interaction and the durability to laundering of a cationic β‐cyclodextrin derivative applied to Tencel were examined by x‐ray photoelectron spectroscopy (XPS). The N1(s) XPS spectra of the cationic β‐cyclodextrin treated substrates revealed the presence of the applied finish on the fibre surface and that the durability of the applied finish to hand‐wash was good. However, the cationic β‐cyclodextrin derivative showed poor durability to the ISO CO6/C2S wash protocol. Copyright © 2009 John Wiley & Sons, Ltd.     

One‐step strategy for the synthesis of a derivatized cyclodextrin‐based monolithic column

Derivatized β‐cyclodextrin (β‐CD) functionalized monolithic columns were prepared by a “one‐step” strategy using click chemistry. First, the intended derivatized β‐CD monomers were synthesized by a click reaction between propargyl methacrylate and mono‐6‐azido‐β‐CD and then sulfonation or methylation was carried out. Finally, monolithic columns were prepared through a one‐step in situ copolymerization of the derivatized β‐CD monomer and ethylene glycol dimethacrylate. The sulfated β‐CD‐based monolith was successfully applied to the hydrophilic interaction liquid chromatography separation of nucleosides and small peptides, while the methylated β‐CD‐functionalized monolith was useful for the separation of nonpolar compounds and drug enantiomers in capillary reversed‐phase liquid chromatography. The structures of the monomers were characterized by Fourier transform infrared spectroscopy and mass spectrometry. The physicochemical properties and column performance of monoliths were evaluated by scanning electron microscopy and micro high performance liquid chromatography. This strategy has considerable prospects for the preparation of other derivatized CD‐functionalized methacrylate monoliths.     

Enantiomeric separation of 2‐arylpropionic acid nonsteroidal anti‐inflammatory drugs by HPLC with hydroxypropyl‐β‐cyclodextrin as chiral mobile phase additive

The enantio‐separations of eight 2‐arylpropionic acid nonsteroidal anti‐inflammatory drugs (2‐APA NSAIDs) were established using reversed‐phase high‐performance liquid chromatography with hydroxypropyl‐β‐cyclodextrin (HP‐β‐CD) as chiral mobile phase additive for studying the stereoselective skin permeation of suprofen, ketoprofen, naproxen, indoprofen, fenoprofen, furbiprofen, ibuprofen and carprofen. The effects of the mobile phase composition, concentration of HP‐β‐CD and column temperature on retention and enantioselective separation were investigated. With 2‐APA NSAIDs as acidic analytes, the retention times and resolutions of the enantiomers were strongly related to the pH of the mobile phase. In addition, both the concentration of HP‐β‐CD and temperature had a great effect on retention time, but only a slight or almost no effect on resolutions of the analytes. Enantioseparations were achieved on a Shimpack CLC‐ODS (150 × 4.6 mm i.d., 5 μm) column. The mobile phase was a mixture of methanol and phosphate buffer (pH 4.0–5.5, 20 mM) containing 25 mM HP‐β‐CD. This method was flexible, simple and economically advantageous over the use of chiral stationary phase, and was successfully applied to the enantioselective determination of the racemic 2‐APA NSAIDs in an enantioselective skin permeation study. Copyright © 2009 John Wiley & Sons, Ltd.     

Synthesis of β‐Haloketones by β‐Addition Reactions of α,β‐Unsaturated Ketones with BX3 (X = Br,Cl) as Halide Source

A series of β‐bromoketones and β‐chloroketones were synthesized by the addition reactions of α,β‐unsaturated ketones under BX₃ (X = Br, Cl) and ethylene glycol reaction system. The α,β‐unsaturated ester also was successfully converted to its corresponding β‐bromoester under the reaction condition.     

Triphenylphosphine‐Mediated Reduction of Electron‐Deficient Propargyl Ethers to the Allylic Ethers

Semihydrogenation of α,β‐unsaturated ynoates and ‐ynones bearing a γ‐alkoxy group can be performed using triphenylphosphine and water. α,β‐Unsaturated ynoates were reduced to a mixture of cis and trans α,β‐unsaturated enoates, whereas, ynones were reduced to trans α,β‐unsaturated enones as the only products.     

Synergistic effects of β‐cyclodextrin containing silicone oligomer on intumescent flame retardant polypropylene system

The effects of β‐cyclodextrin containing silicone oligomer(CDS), as a synergistic agent, on the flame retardancy and mechanical properties of intumescent flame retardant polypropylene composites were studied by adding different amounts of CDS in intumescent flame retardants. The limiting oxygen index (LOI), UL‐94 test, thermogravimetric analysis (TGA), and scanning electron microscopy (SEM) were utilized to evaluate the synergistic effects of CDS in the composites. It was found that after a little amount of CDS partially replaced a charring‐foaming agent (CFA) in IFR, LOI values of the composites were enhanced and they obtained a UL‐94 V‐0 rating. IFR system containing 6.25wt% CDS presented the best flame retardancy in PP. The experimental results obtained from LOI and UL‐94, TGA, SEM, and mechanical properties indicated that the combination of CDS and CFA presents synergistic effects in flame retardancy, char formation, and mechanical properties of the composites. This is probably due to different structures of polyhydroxyl macromolecules (CDS and CFA), the existence of dimethyl silicone group in CDS, and the toughness of epoxy silicon chain in CDS. SEM results proved that the interfacial compatibility between IFR and PP was improved by CDS. Copyright © 2009 John Wiley & Sons, Ltd.     

Preparation and characterization of poly(ethylene oxide)‐loaded hydroxypropyl‐β‐cyclodextrin nanofibers

Hydroxypropyl‐β‐cyclodextrin (HP‐β‐CD) is a modified β‐cyclodextrin (β‐CD) derivative, which is toxicologically harmless to mammals and other animals. HP‐β‐CD is electrospun from an aqueous solution by blending with a non‐toxic, biocompatible, synthetic polymer poly(ethylene oxide) (PEO). Aqueous solutions containing different HP‐β‐CD/PEO blends (50:50–80:20) with variable concentrations (4 wt%–12 wt%) were used. Scanning electron microscope was used to investigate the morphology of the fibers, and Fourier transform infrared spectroscopy analysis confirmed the presence of HP‐β‐CD in the fiber. Uniform nanofibers with an average diameter of 264, 244, and 236 nm were obtained from 8 wt% solution of 50:50, 60:40, and 70:30 HP‐β‐CD/PEO, respectively. The average diameter of the fiber was decreased with increasing of HP‐β‐CD/PEO ratio. However, a higher proportion of HP‐β‐CD in the spinning solution increased beads in the fibers. The polymer concentration had no significant effect on the fiber diameter. The most uniform fibers with the narrowest diameter distribution were obtained from the 8 wt% of 50:50 solution. Copyright © 2015 John Wiley & Sons, Ltd.     

Modular β‐cyclodextrin and polyoxyethylene ether modified water‐soluble polyacrylamide for shale hydration inhibition

A novel water‐soluble copolymer was prepared from acrylamide (AM), acrylic acid (AA), mono‐2‐O‐(allyloxy‐2‐hydroxyl‐propyl)‐β‐cyclodextrin (O‐β‐CD) and allyl alcohol polyoxyethylene ether (APEG), which was characterized with infrared spectroscopy, proton nuclear magnetic resonance spectroscopy, ¹³C‐nuclear magnetic resonance spectrometry and static light scattering. This new copolymer combining polyglycols and the massive hydroxyl groups and cavity structure of β‐CD was investigated for inhibiting shale hydration. Based on the salt‐tolerance test, thermogravimetric‐differential scanning calorimetry‐mass spectrometer analyses, copolymer AM/AA/APEG/O‐β‐CD has made progress in the salt and temperature resistances. Moreover, the remarkable inhibiting‐hydration performance of copolymer was found as evidenced by the reduction of interlayer spacing of sodium montmorillonite and the high retention rates of indentation hardness of shale cores. Copyright © 2015 John Wiley & Sons, Ltd.     

A Cyclodextrin Microgel for Controlled Release Driven by Inclusion Effects

Summary: A novel intelligent delivery system based on the environmental dependence of the inclusion effect of β‐cyclodextrin (β‐CD) with guest molecules, using a β‐CD polymer (CDP) microgel as carrier, is proposed. Compared with smart hydrogels, which are driven by the phase‐volume transition, controlled release from the CDP microgel is driven by “host‐guest” inclusion effects. With the pH‐dependent inclusion complexation of methyl orange (MO) with β‐CD as a model system, the behavior of the controlled release of a CDP microgel was tested by changing the pH, showing that the mechanism is reasonable.

Schematic illustration of the pH‐dependent inclusion complexation of MO with β‐CD in the CDP microgel.