High‐Pressure 31P{1H} NMR Studies of RhH(CO)(TPPTS)3 in the Presence of Methylated Cyclodextrins: New Light on Rhodium‐Catalyzed Hydroformylation Reaction Assisted by Cyclodextrins

The effect of methylated cyclodextrins on the RhH(CO)(TPPTS)₃ complex in hydroformylation conditions [50 atm of CO/H₂ (1/1) and 80 °C] has been investigated by high‐pressure ³¹P{¹H} NMR spectroscopy. In the presence of methylated β‐cyclodextrin, the equilibria between the rhodium species lie in favor of phosphine low‐coordinated rhodium species. The formation of a stable inclusion complex between this cyclodextrin and the trisulfonated triphenylphosphine ligand (TPPTS) was found to be the key to understanding the displacement of the equilibria. Indeed, the methylated α‐cyclodextrin which does not interact with the TPPTS and the methylated γ‐cyclodextrin which can weakly bind to the TPPTS have no and a very low effect on the equilibria, respectively. These results explain for the first time why a decrease in the normal to branched aldehydes ratio is always observed when cyclodextrins are used as mass‐transfer agents in aqueous biphasic hydroformylation processes.     

Synthesis of a novel linear water‐soluble β‐cyclodextrin polymer

A novel linear water‐soluble β‐cyclodextrin polymer has been prepared by grafting β‐cyclodextrin on poly[(methyl vinyl ether)‐alt‐(maleic anhydride)]. First, lithium hydride was used to obtain the mono‐alkoxide β‐CD. Grafting of β‐CD derivatives to the polymer backbone was then carried out by an esterification method. Using this method, polymers containing various amounts of β‐CD were synthesized. The resulting grafted polymers were characterized by two complementary methods, ¹H NMR and IR spectroscopy. The first was used to calculate the degree of substitution for the low amounts of β‐CD. The second method was very useful to evaluate the degree of substitution and the molar ratio of CD especially for high amounts of grafting. Our results indicate good agreement between both methods for intermediate rates. Copyright © 2004 Society of Chemical Industry     

Molecular recognition: polymers comprising isomeric meta‐/para‐isopropylphenol and N‐isopropylacrylamide and their supramolecular complexes with methylated β‐cyclodextrin

We describe the molecular recognition of polymeric attached isomers meta‐isopropylphenol and para‐isopropylphenol, respectively, in a copolymer of N‐isopropylacrylamide (NIPAAm) by use of randomly methylated β‐cyclodextrin (RAMEB‐CD). The acrylic monomers 4‐ and 3‐isopropylphenylacrylate were synthesized and radically copolymerized with NIPAAm yielding the corresponding polymers. The supramolecular structures resulting from complexation with RAMEB‐CD were characterized using dynamic light scattering, turbidity, NMR spectroscopy and isothermal titration. We found differences in binding constant, mean coil size and cloud point as a result of different complexations of the mentioned polymer‐bound isomers with RAMEB‐CD. Copyright © 2012 Society of Chemical Industry     

Preparation of bimodal porous copolymer containing β‐cyclodextrin and its inclusion adsorption behavior

A novel insoluble bimodal porous polymer containing β‐cyclodextrin (β‐CD) was prepared to adsorb aromatic amine compound. The process involved copolymerization of styrene and methyl methacrylate with a maleic acid derivative of β‐CD, subsequently, above formed copolymer was foamed by supercritical CO₂. The chemical properties and physical structure of obtained copolymer was analyzed using Fourier transform infrared spectra, Thermal gravimetric analysis, X‐ray diffraction, scanning electron microscope, and N₂ adsorption techniques. The inclusion adsorption of aromatic amine compounds on β‐CD copolymer was carried out in a batch system. The quantities of aromatic amine compounds adsorbed on β‐CD copolymer reached equilibrium within 60 min. The adsorption kinetic could be fitted to a pseudo‐second‐order kinetic equation, and the linear correlation coefficients varied from 0.9828 to 0.9935. With the influence of molecular structure and hydrophobicity of the aromatic amine compound, the sequence of quantity of aromatic amine compounds adsorbed on β‐CD copolymer is p‐toluidine > aniline > benzidine > o‐toluidine. The adsorption equilibrium data of aromatic amine compound adsorbed on β‐CD copolymer were fitted to Freundlich and Langmuir models, respectively. The linear correlation coefficients of Langmuir model varied from 0.9516 to 0.9940, and the linear correlation coefficients of Freundlich varied from 0.9752 to 0.9976. It is concluded that Freundlich model fits better than Langmuir model, because the adsorption of aromatic amine compound on β‐CD copolymer is a chemical process. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Preparation and characterization of a novel responsive hydrogel with a β‐cyclodextrin‐based macromonomer

Based on a combination of poly(N‐isopropylacrylamide), which could respond to an external temperature, and β‐cyclodextrin (β‐CD), which could form a molecular inclusion complex, a novel hydrogel, having both thermal and pH sensitivities and containing β‐CD and N‐isopropylacrylamide (NIPA) segments, was synthesized. For the incorporation of β‐CD into the polymer network, a macromonomer was prepared first by the reaction of a β‐CD‐based polymer with maleic anhydride in dimethylformamide and then by copolymerization with NIPA in an aqueous solution. Elemental analysis, IR spectroscopy, differential scanning calorimetry, and swelling measurements were employed for the characterization of the hydrogel chain structure and its physical properties. With methyl orange as a model compound in inclusion tests, it was found that the hydrogel not only possessed a remarkable supramolecular inclusion ability (with respect to that of the small molecule cyclodextrin) but also could sensitively respond to various external stimuli, including the temperature, pH, and ionic strength. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 361–367, 2003     

Heptakis(2,3‐di‐O‐methyl‐6‐O‐sulfopropyl)‐β‐cyclodextrin: A Genuine Supramolecular Carrier for Aqueous Organometallic Catalysis

The behavior of heptakis(2,3‐di‐O‐methyl‐6‐O‐sulfopropyl)‐β‐cyclodextrin as inverse phase transfer catalyst in biphasic Tsuji–Trost and hydroformylation reactions has been investigated. In terms of activity, this methylated sulfopropyl ether β‐cyclodextrin is much more efficient than the randomly methylated β‐cyclodextrin, which was the most active cyclodextrin known to date. From a selectivity point of view, the intrinsic properties of the catalytic system are fully preserved in the presence of this cyclodextrin as the chemo‐ or regioselectivity was found to be identical to that observed without a mass transfer promoter in the hydroformylation reaction. The efficiency of this cyclodextrin was attributed to its high surface activity and to the absence of interactions with the catalytically active species and the water‐soluble phosphane used to dissolve the organometallic catalyst in the aqueous phase.     

Rhodium‐Catalyzed Hydrogenation of Alkenes by Rhodium/Tris(fluoroalkoxy)phosphane Complexes in Fluorous Biphasic System

The reaction of [Ir(μ‐Cl)(COD)]₂ with various fluorous derivatives of triphenylphosphane containing a para‐, meta‐, or ortho‐(1H,1H‐perfluoroalkoxy)‐substituted fluorous phosphane P(C₆H₄‐ORf)₃ (Rf=CH₂C₇F₁₅, CH₂CH₂CH₂C₈F₁₇) and CO (1 atm) gives the corresponding trans‐[Ir(μ‐Cl)(CO){P(C₆H₄ORf)₃}₂]. The IR ν_CO values of these complexes give some information on the donor/acceptor properties of the phosphanes. These fluorous derivatives of triphenylphosphane, as well as a phosphane bearing two (1H,1H‐perfluoroalkyloxy) chains at the 3,5‐positions, were used in association with [Rh(μ‐Cl)(COD)]₂ or [Rh(COD)₂]PF₆ in the reduction of methyl cinnamate, 2‐cyclohexen‐1‐one, cinnamaldehyde, and methyl α‐acetamidocinnamate in a two‐phase system D‐100/ethanol under 1 bar hydrogen at room temperature. Some differences in catalytic activity were observed in the reduction of methyl cinnamate, the most active catalyst being the rhodium complex containing the phosphane with the p‐fluorous ponytail. Recycling of the fluorous catalyst was possible, particularly using the p‐substituted phosphane, where no significant loss of catalyst or activity was observed, and generally with very low leaching of rhodium or phosphane in the organic phase.     

Sulfobutyl Ether‐β‐Cyclodextrins: Promising Supramolecular Carriers for Aqueous Organometallic Catalysis

The potentialities of sulfobutyl ether‐β‐CDs derivatives as supramolecular carrier in a biphasic Tsuji–Trost reaction catalyzed by a water‐soluble palladium complex of trisulfonated triphenylphosphine have been investigated. The efficiency of these cyclodextrins (CDs) strongly depends on the average molar substitution degree of cyclodextrin and the highest rate enhancements were obtained with cyclodextrins containing about 7 sulfobutyl ether groups. This result was attributed to the absence of a strong interaction between this cyclodextrin and the trisulfonated triphenylphosphine used to dissolve the catalyst in the aqueous phase and to the presence of an extended hydrophobic cavity allowing a better molecular recognition between the substrate and the cyclodextrin. This constitutes the first example of a non‐interacting β‐cyclodextrin/phosphine couple with high catalytic activities.     

Viscometric Study of the Inclusion Complex Between β‐Cyclodextrin and HTAC in Aqueous Solution

The inclusion complex formed by β‐cyclodextrin (β‐CD) with the cationic surfactant hexadecyltrimethylammonium chloride (HTAC) was studied by viscometry using poly(ethylene oxide) (PEO)–HTAC aggregates as a viscosity indicator. The relative viscosity of β‐CD in aqueous PEO–HTAC solution profiles shows that the formation of the β‐CD/HTAC inclusion complex causes HTAC molecules to be stripped off the PEO chains, resulting in a decrease of aqueous solution viscosity as a result of the decrease in electrostatic repulsion between polymer‐bound HTAC micelles. The viscosity minimum at C_β‐CD/C_HTAC = 0.5 indicates that the molecular ratio of host molecule to guest molecule is 1:2 in the β‐CD/HTAC inclusion complex.     

Synthesis and characterization of grafting β‐cyclodextrin with chitosan

Two new adsorbents [β‐cyclodextrin–chitosan (β‐CD–CTS) and β‐cyclodextrin‐6–chitosan (β‐CD‐6‐CTS)] were synthesized by the reaction of β‐cyclodextrin (β‐CD) with epoxy‐activated chitosan (CTS) and the sulfonation of the C‐6 hydroxyl group of β‐cyclodextrin with CTS, respectively. Their structures were confirmed by IR spectral analysis and X‐ray diffraction analysis, and their apparent amount of grafting was determined by ultraviolet spectroscopy. The adsorption properties of β‐CD‐CTS and β‐CD‐6‐CTS for p‐dihydroxybenzene were studied. The experimental results showed that the two new adsorbents exerted adsorption on the carefully chosen target. The highest saturated capacity of p‐dihydroxybenzene of β‐CD‐CTS and β‐CD‐6‐CTS were 51.68 and 46.41 mg/g, respectively. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 860–864, 2004     

Synthesis,Rhodium Complexes and Catalytic Applications of a New Water‐Soluble Triphenylphosphane‐Modified β‐Cyclodextrin

A new triphenylphosphane based on a β‐cyclodextrin skeleton (PM‐β‐CD‐OTPP) was synthesized. This ligand can be dispersed in water by using the nanoprecipitation method. Transmission electron microscopy and NMR spectroscopy showed that PM‐β‐CD‐OTPP is aggregated in water and forms a stable dispersion. Its aqueous solubility can be dramatically increased in the presence of selected water‐soluble guests by formation of inclusion complexes. Associated to a rhodium precursor, PM‐β‐CD‐OTPP is able to generate soluble rhodium species in water. In addition, NMR experiments showed that the cyclodextrin cavity remains accessible for a guest even when PM‐β‐CD‐OTPP is coordinated to rhodium. Finally, this ligand was efficient for rhodium‐catalyzed hydrogenation and hydroformylation performed in aqueous medium.     

A facile and practical approach to randomly methylated β‐cyclodextrin

BACKGROUND: Because of its high demand for use in pharmaceutical products, cosmetics, soil remediation technologies, etc., randomly methylated β‐cyclodextrin (RM‐β‐CD) is one of the most important cyclodextrin (CD) derivatives. The aim of this present work is to use a green and commercially available approach to obtain RM‐β‐CD. Compared with other methylated CDs, RM‐β‐CD with an asymmetric molecular structure has higher water solubility. When the degree of substitution (DS) is about 1.8, the solubility tends to increase with increasing temperature and is suitable for pharmaceutical applications. RESULTS: RM‐β‐CD was synthesized using a green approach with ideal DS equal to 1.79. The one step process of β‐cyclodextrin methylation by CH₃Cl instead of (CH₃)₂SO₄ at mild temperature (80 °C) and pressure (1.60 MPa) with a good yield (78%), is convenient and environmentally friendly. The mixture of RM‐β‐CD obtained contained five compounds with various DS, from which the main compound with a DS equal to 1.8 was separated by column chromatography. The compounds were carefully characterized by infra‐red, NMR and mass spectrometry. CONCLUSIONS: The one‐step process to RM‐β‐CDs with CH₃Cl is more economical, more efficient and less noxious than the usual method using (CH₃)₂SO₄. Moreover, this approach avoids some poisonous residual materials and meets the demand for protecting the environment. Copyright © 2009 Society of Chemical Industry     

Inclusion complex of cantharidin with β‐cyclodextrin: Preparation,characterization, in vitro and in vivo evaluation

Because of low aqueous solubility and slow dissolution rate, cantharidin has a low oral bioavailability. Our research aims to prepare the inclusion complex of cantharidin and β‐cyclodextrin (β‐CD) and accomplish characterization, in vitro and in vivo evaluation. CA‐β‐CD inclusion complex was prepared by saturated solution method. The CA was demonstrated by HPLC in vitro experiment and by GC‐MS in vivo experiment. CA‐β‐CD inclusion complex was characterized by differential scanning calorimetry (DSC), X‐ray diffractometry (XRD), and nuclear magnetic resonance (NMR). Through complexation with β‐CD, the solubility of CA in neutral aqueous solution was improved significantly. CA‐β‐CD inclusion complex also shows a significantly improved dissolution rate in comparison with free CA. Comparison of the pharmacokinetics between CA‐β‐CD inclusion complex and free CA was performed in rats. The in vivo results show that CA‐β‐CD inclusion complex has earlier t_max, higher C_max, and higher bioavailability than free CA after oral dosing. By comparing the AUC_0–t of CA and CA‐β‐CD inclusion complex, the relative bioavailability of CA‐β‐CD inclusion complex to free CA was 506.3%, which highlighted the evidence of significantly improved bioavailability of formulation of CA with β‐CD. Thus, this β‐CD‐based drug delivery system should be an effective oral dosage form to improve oral bioavailability of CA. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Preparation and characterization of molecular photoresists: Crosslinkable positive and water developable negative tones

The development of a water‐developable negative photoresist from β‐CD using an acid‐catalyzed chemical amplification method is investigated here. Tertiary butoxyl protected β‐cyclodextrin (t‐BOC‐CD) is also synthesized and used to prepare a positive photoresist. Glutaraldehyde is added as a crosslinking agent for both positive and negative photoresists. Deprotection of t‐BOC‐CD is accelerated by a photo‐induced acid. In the presence of glutaraldehyde and acid, both the deprotected t‐BOC‐CD and β‐cyclodextrin are crosslinked. The introduction of a t‐butoxyl group into the β‐CD molecule and the addition of glutaraldehyde into the β‐CD molecules are both found to decrease the crystallinity of the molecules, improving the resist film properties. The etching resistance of both positive and negative photoresist films is improved by the crosslinking method. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

C‐3 Selective Ring Opening of 2,3‐Aziridino Alcohols and their Derivatives with Nucleophiles in the Presence of β‐Cyclodextrin in Water

For the first time a mild and efficient procedure has been developed for the C‐3 selective ring opening, under biomimetic conditions, of 2,3‐aziridino alcohols and their derivatives with nucleophiles such as aromatic thiols and amines catalyzed by β‐cyclodextrin in water at room temperature to afford the corresponding β‐amino sulfides and diamines with high regioselectivity in impressive yields. The use of cyclodextrin precludes the use of either acid or base and the catalyst can be recovered and reused.     

Preparation and characterization of a temperature‐sensitive nonwoven poly(propylene) with increased affinity for guest molecules

A temperature‐sensitive hydrogel with the capability of inclusion complex formation with guest molecules was successfully grafted onto the surface of nonwoven polypropylene (nonwoven PP). This was carried out by the use of N‐isopropylacrylamide monomer and a modified cyclodextrin (acrylamidomethyl‐β‐cyclodextrin (β‐CD‐NMA)). Fourier‐transform infra red (FT‐IR) and elemental analyses confirmed the presence of poly(N‐isopropylacrylamide) (PNIPAAm) and β‐CD‐NMA components on the surface of the textile. Equilibrium swelling ratio measurements showed that the grafted hydrogel maintained its temperature‐sensitive property compared to a nongrafted hydrogel. The effect of β‐CD‐NMA and crosslink agent concentrations on the grafting yield was studied. The β‐CD‐NMA content into the PNIPPAM‐ β‐CD‐NMA grafted nonwoven PP (PNIPAAm‐β‐CD‐NMA‐PP) was estimated by FT‐IR through a new procedure. The estimated amounts of β‐CD‐NMA in PNIPAAm‐β‐CD‐NMA‐PP were determined to be 0.9, 1.9 mg g^?1 for 0.019M and 0.049M concentrations of β‐CD‐NMA in monomer solution, respectively. The PNIPAAm‐β‐CD‐NMA‐PP showed a remarkable increase in absorbance affinity of 8‐anilino‐1‐naphthalenesulfonic acid ammonium salt at 20°C from 0.93 to 3.33 µmol g^?1 compared to PNIPAAm‐PP. Furthermore, the results showed a temperature‐sensitive loading affinity for PNIPAAm‐β‐CD‐NMA‐PP in absorbance of guest molecules due to the presence of β‐CD‐NMA. The use of hydrophobic guest molecules such as fragrance oils and antibiotics in modified fabrics can provide new applications in textile and pharmaceutical industry. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40497.     

A water‐soluble supramolecular‐structured photoinitiator between methylated β‐cyclodextrin and 2,2‐dimethoxy‐2‐phenylacetophenone

A water‐soluble supramolecular‐structured photoinitiator (SSPI) was synthesized by supramolecular self‐assembling between methylated β‐cyclodextrin (MβCD) and hydrophobic 2,2‐dimethoxy‐2‐phenylacetophenone (DMPA). The structure of SSPI was characterized by X‐ray diffraction, FTIR, ¹H NMR, UV–vis, and fluorescence spectra. The results indicated that MβCD and DMPA had formed 1 : 1 inclusion complex in methanol solution. The binding constant (K) for the complex was 7.51 × 10²M^?1. SSPI could be dissolved in water easily and its water‐solubility was 15.3 g/100 mL. SSPI was the more efficient photoinitiator than DMPA for the photopolymerization of acrylamide (AM) in homogeneous aqueous system. The conversion for photopolymerization of trimethylolpropane triacrylate system initiated by SSPI was similar to that initiated by DMPA. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Permanent fixation of β‐cyclodextrin on cotton surface—An assessment between innovative and established approaches

Attachment of β‐cyclodextrin (β‐CD) molecules on cotton textile provides hosting cavities that can include a large variety of guest molecules for specific functionality. Five different new and existing techniques were evaluated for connecting β‐CD and its derivatives to cotton surface. A comparison has been made in terms of maximum attachment of β‐CD on cotton surface. Novel chemical based crosslinking with homo‐bi‐functional reactive dye (C.I. reactive black 5) and grafting with reactive monochlorotriazinyl‐β‐cyclodextrin show maximum attachment to cotton surface. Innovative, enzymatic coupling of especially synthesized 6‐monodeoxy‐6‐mono(N‐tyrosinyl)‐β‐cyclodextrin was performed on cotton textile surface. Enzymatic coupling was also carried out in a homogeneous system and attachment confirmed by UV–vis spectroscopy. This tyrosinase mediated coupling is low temperature and very specific technique. A phenolphthalein based analytical method was partially modified to reliably measure the amount of attached β‐CD on cotton surface. Atomic force microscopy and scanning electron microscopy techniques were used for surface characterization of the treated and untreated cotton surfaces. Alteration in surface topography has been observed for β‐CD treated samples. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Hydrophobically modified poly[(divinyl ether)‐co‐(maleic anhydride)]: interactions with cyclodextrin derivatives and hydrogel formation

Hydrolyzed cyclocopolymer prepared from divinyl ether and maleic anhydride, poly[(divinyl ether)‐ co ‐(maleic anhydride)] (DIVEMA), was functionalized with aminoadamantane and subsequently compared with the hydrolyzed DIVEMA with respect to physicochemical properties. The complexation behavior of adamantyl modified DIVEMA with cyclodextrin derivatives was examined by dynamic light scattering, nuclear magnetic resonance spectroscopy and zeta potential. The scattering studies indicated the formation of well‐defined aggregated structures with an average diameter of 120 nm. These aggregated structures collapsed on addition of randomly methylated β‐cyclodextrin to give 4.2 nm in hydrodynamic diameter. Interactions with crosslinked β‐cyclodextrins indicated gel formation which was analyzed by means of rheology and temperature‐dependent viscosity showing disaggregation of the host‐guest system at 42 °C. This novel physical hydrogel is very interesting for medical applications as a drug delivery system with included anti‐tumor activity. Copyright © 2012 Society of Chemical Industry     

Up to 96% Enantioselectivities in the Hydrogenation of Fluorine Substituted (E)‐2,3‐Diphenylpropenoic Acids over Cinchonidine‐Modified Palladium Catalyst

The enantioselective hydrogenation of methoxy‐ and fluorine‐substituted (E)‐2,3‐diphenylpropenoic acid derivatives was studied over cinchonidine‐modified, supported palladium catalysts in the absence and presence of benzylamine as additive. The fluorine substituent in the appropriate position was even more efficient than the methoxy group in increasing the optical purity of the saturated product. High enantioselectivities, up to 96%, were obtained in the hydrogenation of some disubstituted derivatives, unprecedented in the hydrogenation of prochiral unsaturated carboxylic acids over modified heterogeneous catalyst. The best optical purities were reached in the hydrogenation of derivates bearing a para‐substituent on the β phenyl and an ortho‐substituent on the α phenyl ring, respectively. The influence of the substituent on the β phenyl ring was attributed to the increase in the efficiency of the modifier‐substrate interaction by electronic effects or to a decrease in the adsorption strength of the substituted acid over modified surface sites. The beneficial effect of the ortho‐substituent on the α phenyl ring was assumed to be due to the additional interaction of this substituent with the modifier on the surface, its steric hindrance contributing only in a small part to the observed effect. These suggestions were supported by results obtained in the hydrogenations of some methyl‐substituted derivatives.