Two‐Phase Hydroformylation of Higher Olefins Using Randomly Methylated α‐Cyclodextrin as Mass Transfer Promoter: A Smart Solution for Preserving the Intrinsic Properties of the Rhodium/Trisulfonated Triphenylphosphine Catalytic System

The two‐phase hydroformylation of higher olefins with the rhodium/trisulfonated triphenylphosphine catalytic system in the presence of various chemically modified α‐cyclodextrins has been investigated. These cyclodextrins allowed us to increase greatly the reaction rate and the chemoselectivity of the reaction but, contrary to what has been observed previously with the chemically modified β‐cyclodextrins, the linear to branched aldehydes ratio was not affected by the presence of α‐cyclodextrin derivatives. Indeed, the latter was found to be similar to that obtained without any mass transfer promoter, suggesting that the catalytic species are stable in the presence of α‐cyclodextrin derivatives.     

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.     

A novel insulin oral delivery system assisted by cationic β‐cyclodextrin polymers

This work describes a new oral pharmaceutical formulation of insulin that is complexed with cationic β‐cyclodextrin polymers (CPβCDs), and then encapsulated into alginate/chitosan microspheres, which are prepared by ionotropic pregelation/polyelectrolyte method. CPβCDs were synthesized through a one‐step polymerization of β‐cyclodextrin (βCD), epichlorohydrin, and choline chloride. CPβCDs have enhanced ability to complex with insulin due to the assistance of their polymeric chains, as well as the electrostatic interactions between insulin (negatively charged while pH>5.3) and quaternary ammonium groups of CPβCDs. The noncovalent inclusion complex formed between CPβCDs and insulin was analyzed by Fourier transform infrared and fluorescence emission spectra. With the increase of zeta potential of CPβCDs from 1.8 to 14.2 mV, the insulin association efficiency (AE) of current system was increased from 55.2 to 71.8%, whereas the AE of insulin‐loaded microspheres at the same condition was only 50.7%. The cumulative insulin release in simulated intestinal fluid was also higher than that of the insulin‐loaded microspheres and βCD‐insulin encapsulated microspheres. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

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     

Synthesis of β‐cyclodextrin‐based dendrimer as a novel encapsulation agent

The aim was the fabrication of glycodendrimer encapsulation agents with high proportions of cyclodextrins (CDs) to maintain the biocompatibility properties, as well as to notably improve their ability to load various suitably sized drugs. The novel glycodendrimers contained β‐CD in both core and branches, namely β‐cyclodextrin‐based dendrimer (CD‐dendrimer) prepared through a straightforward procedure using S_N2 displacement to attach multivalent β‐CDs together. The desired CD‐dendrimer was synthesized in three steps: (i) reaction of β‐CD with p‐toluenesulfonyl chloride and/or iodine to afford C‐6 mono‐ and/or per‐β‐CD derivative; (ii) reaction of the β‐CD precursors with ethylenediamine to give C‐6 mono‐ and/or per‐amino‐β‐CD derivative; and (iii) S_N2 displacement of β‐CD electrophilic derivative with β‐CD nucleophilic derivative in dimethylsulfoxide to provide the CD‐dendrimer. Then, the encapsulation behaviour of the CD‐dendrimer was examined using naproxen and naltrexone as the guest molecules. The structure of the designed CD‐dendrimer allowed two types of possible sites for encapsulation of the guest: in cavities of the dendritic structure and in hydrophobic cavities of CDs. © 2013 Society of Chemical Industry     

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.     

Biphasic Aqueous Organometallic Catalysis Promoted by Cyclodextrins: How to Design the Water‐Soluble Phenylphosphane to Avoid Interaction with Cyclodextrin

The ability of cyclodextrin to interact with meta‐trisulfonated triphenylphosphane derivatives bearing one or two methyl (or methoxy) groups on the aromatic ring has been investigated by NMR and UV‐vis spectroscopy. In the case of native β‐cyclodextrin (β‐CD), the presence of one methyl or methoxy group in the ortho‐position on each aromatic ring is necessary to hamper the formation of an inclusion complex between the β‐CD and meta‐trisulfonated triphenylphosphane derivatives. In the case of methylated β‐CD, the formation of an inclusion complex is only observed when the meta‐trisulfonated triphenylphosphane contains a methyl group in the para‐position. The poor affinity of methylated β‐CD towards modified trisulfonated triphenylphosphanes was attributed to the steric hindrance generated by the methyl groups on the CD secondary face. The absence or presence of an interaction between phosphanes and methylated β‐CD was also confirmed by catalytic experiments. Thus, the phosphanes that do not interact with the methylated CD were the most efficient mass‐transfer promoters in an aqueous biphasic palladium‐catalyzed Tsuji–Trost reaction.     

Palladium on Calcium Carbonate Combined to 2‐Hydroxypropyl‐α/β‐cyclodextrins: A Selective Catalytic System for Aqueous Heck Coupling and Hydroarylation

An efficient, selective and recoverable catalytic system for ligand‐free aqueous Heck reactions using hydroxypropylated cyclodextrins (HPCDs) and palladium on calcium carbonate (Pd/CaCO₃) is highlighted. Remarkably, stereo‐ and chemoselectivities could be tuned by the cavity size of cyclodextrins, exploiting the relevance of host‐guest interactions. UV‐Vis experiments have led to strong evidence concerning an interplay between Pd(II) and α‐HPCD, possibly ascribed to a reduction/stabilization effect of CDs. Unexpectedly, hydroarylation was the favored pathway with acrylonitrile which provided access to 3‐phenylpropionitrile derivatives without usual hydride donors. Finally, determination of soluble Pd(0/II) via AAS enabled the definition of a predominant homogeneous mechanism in which TONs over 5000 were observed.     

Equalizing effect of β‐cyclodextrin on dyeing of polyamide 6,6 woven fabrics with acid dyes

Cyclodextrins (CD) are produced from starch by the action of cyclodextrin glycosyltransferase (CGTase) enzyme. Structurally, cyclodextrins consist of 6, 7, or 8 (α, β, and γ cyclodextrins, respectively) D‐glucopyranosyl units connected by α‐(1,4) glycosidic linkages. Having polar and hydrophilic outer sides and hydrophobic cavitation gives cyclodextrins a chance to form inclusion complexes with dyes in hydrophilic mediums. In this research, the equalizing effect of β‐cyclodextrins in dyeing of polyamide 6,6 woven fabrics with 6 different acid dyes were investigated. From the experimental results, it was determined that the β‐cyclodextrin shows a retarding and equalizing effect in dyeings carried out with the dyes that show interaction with β‐CD. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2660–2668, 2007     

Surface treatments on Tencel fabric: Grafting with β‐cyclodextrin

Tencel is a cellulosic fabric obtained from wood pulp that is very similar to natural cotton. For its potential performances to be expanded, Tencel needs to be processed in different ways. The ability of cyclodextrins to include hydrophobic molecules, such as fragrances, antimicrobial agents, and other chemicals, can be exploited to produce new grafted textiles with peculiar performances. We report studies on the grafting of acrylamidomethylated β‐cyclodextrin and monochlorotriazinyl‐β‐cyclodextrin to Tencel and on the inclusion of different molecules in the free cavities of cyclodextrins. The physicochemical properties and performances of the untreated and treated fabric have been determined with differential scanning calorimetry, ultraviolet–visible spectra, X‐ray diffractometry, and breaking load loss, aroma, and antimicrobial finishing tests. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 706–715, 2003     

Pervaporation behavior of PVA membrane containing β‐cyclodextrin for separating xylene isomeric mixtures

To evaluate molecular recognition function of β‐cyclodextrin to xylene isomers, β‐CD polymer of branching chain extension (β‐CD‐EGDE) was synthesized by crosslinking β‐CD with ethylene glycol diglycidyl ether (EGDE). The pervaporation blend membranes of β‐CD‐EGDE/PVA were prepared by casting an aqueous solution of PVA and β‐CD polymer mixture, and the membranes were used for separation of p‐/m‐ and p‐/o‐xylene mixtures. It was observed that the pristine PVA membrane almost had no selectivity for xylene isomer mixtures. The PVA membrane incorporating β‐CD polymer had molecular recognition function, which selectively facilitated the transport of the xylene isomers. To ascertain pervaporation behavior, the sorption and desorption processes of the membrane in xylenes were investigated. The sorption result showed that the complex formation constant between β‐CDs and xylenes played a key role in swelling behavior. There was a significant difference between diffusion coefficients D and D⁰, calculated from the sorption and desorption measurements, respectively, indicating that the diffusivity selectivity in desorption stage may have remarkable effect on the total selectivity during pervaporation process. © 2012 American Institute of Chemical Engineers AIChE J, 59: 604–612, 2013     

Click‐coupling of anthraquinone dyes with β‐cyclodextrin: formation of polymeric superstructures

Two novel cyclodextrin‐modified anthraquinone dyes were synthesized and investigated for their complexation behaviour and formation of superstructures. Therefore, 1‐fluoro‐4‐N‐(propargylamino)anthraquinone and 1,4‐bis(propargyloxy)anthraquinone were prepared via nucleophilic aromatic displacement and subsequently covalently ‘click‐coupled’ in a copper(I)‐catalysed azide–alkyne cycloaddition with β‐cyclodextrin monoazide. Both the propargyl‐modified precursor and the click‐coupled anthraquinone dyes were evaluated as hosts and guests, respectively, in β‐cyclodextrin interactions. The anthraquinone dye bearing two cyclodextrins, 1,4‐bis((1‐β‐cyclodextrin‐1H‐1,2,3‐triazol‐5‐yl)methoxy)anthraquinone, enables the reversible formation of supramolecular crosslinked poly[(N,N‐dimethyl acrylamide)‐co‐(N‐(ferrocenoylmethyl)acrylamide)] ( 11 ), whereas the monofunctionalized compound 1‐fluoro‐4‐(((1‐β‐cyclodextrin‐1H‐1,2,3‐triazol‐5‐yl)methyl)amino)anthraquinone can be supramolecularly linked to 11 resulting in coloured polymers. These features of β‐cyclodextrin‐linked anthraquinone dyes can be verified with either ¹H ¹H NMR rotating frame nuclear Overhauser effect spectroscopy or the naked eye. © 2016 Society of Chemical Industry     

Synthesis and characterization of polyrotaxanes comprising α‐cyclodextrins and poly(ε‐caprolactone) end‐capped with poly(butyl methacrylate)s

Biodegradable polyrotaxane‐based triblock copolymers were synthesized via the bulk atom transfer radical polymerization (ATRP) of n‐butyl methacrylate (BMA) initiated with polypseudo‐rotaxanes (PPRs) built from a distal 2‐bromoisobutyryl end‐capped poly(ε‐caprolactone) (Br‐PCL‐Br) with α‐cyclodextrins (α‐CDs) in the presence of Cu(I)Br/N,N,N′,N″,N″‐pentamethyldiethylenetriamine at 45 ºC. The structure was characterized in detail by means of ¹H NMR, gel permeation chromatography, wide‐angle X‐ray diffraction, DSC and TGA. When the feed molar ratio of BMA to Br‐PCL‐Br was changed from 128 to 300, the degree of polymerization of PBMA blocks attached to two ends of the PPRs was in the range 382 ? 803. Although about a tenth of the added α‐CDs were still threaded onto the PCL chain after the ATRP process, the movable α‐CDs made a marked contribution to the mechanical strength enhancement, blood anticoagulation activity and protein adsorption repellency of the resulting copolymers. Meanwhile, they could also protect the copolymers from the attack of H₂O and Lipase AK Amano molecules, exhibiting a lower mass loss as evidenced in hydrolytic and enzymatic degradation experiments. © 2013 Society of Chemical Industry     

Grafting of cotton with β‐cyclodextrin via poly(carboxylic acid)

Cyclodextrins are cyclic oligosaccharides. Cyclodextrin molecules can form inclusion complexes with a large number of organic molecules. The properties of cyclodextrins enable them to be used in a variety of different textile applications. Cyclodextrins can act as auxiliaries in washing and dyeing processes, and they can also be fixed onto different fiber surfaces. Because of the complexing abilities of cyclodextrins, textiles with new functional properties can be prepared. Poly(carboxylic acid)s such as 1,2,3,4‐butane tetracarboxylic acid (BTCA) are well‐known non‐formaldehyde crosslinking reagents. BTCA has four carboxylic acid groups, which can react with hydroxyl groups of cellulose and form stable ester bonds. We crosslinked β‐cyclodextrin molecules on hydroxyl groups of cellulose via BTCA. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1323–1328, 2005     

A recyclable β‐cyclodextrins‐based supramolecular adsorbent for removal of organic dyes

In this article, a novel recyclable β‐cyclodextrins (β‐CDs)‐based supramolecular adsorbent had been fabricated. With Fe₃O₄ magnetic nanoparticles as core, the adsorbent could be separated from water conveniently. Moreover, the hydrophobic β‐CDs caving had strong host‐guest interaction with organic compounds to form complexes. With the pH value changing, the stable complexes would disassemble to recover the adsorbent. Fourier transform infrared analysis, X‐ray diffraction measurement, transmission electron microscopy measurements, thermogravimetric analysis, and vibrating sample magnetometer analysis had been explored to confirm the structure and properties of supramolecular adsorbent. Congo red and Rhodamine B were used to characterize the adsorption capacity of adsorbent. By changing the parameters such as temperature, time, adsorbent dosage, and pH value indicated that the designed adsorbent could rapidly remove organic dyes from water with satisfactory removal effects and adsorbent recycling capacity. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45084.     

Development of antifouling polyamide thin‐film composite membranes modified with amino‐cyclodextrins and diethylamino‐cyclodextrins for water treatment

The fouling behavior of polyamide thin‐film composite (TFC) membranes modified with amino‐ and diethylamino‐cyclodextrins (CDs) through an in situ interfacial polymerization process is reported. Modified polyamide TFC membranes exhibited improved hydrophilicity, water permeability, and fouling resistance as compared to the unmodified TFC membranes, while restricting the passage of NaCl salt (98.46 ± 0.5%). The increase in hydrophilicity was attributed to the secondary and tertiary hydroxyl groups of the CDs, which were not aminated. The membranes modified with amino‐CDs had increased surface roughness while the membranes modified with diethylamino‐CDs had smoother surfaces. However, despite the surface roughness of the membranes modified with amino‐CDs, low fouling was observed due to the highly hydrophilic surfaces, which superseded the roughness. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40109.     

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     

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     

Surface modification using self‐assembled layers of amphiphilic cyclodextrins

In this study six amphiphilic cyclodextrin derivatives were prepared by esterification and used to coat five industrial products made from polypropylene, polyethylene, polyvinyl chloride, or polyurethane using a new, patented coating technology. This simple approach, which consists merely of dipping the material to be coated into a suspension of a given cyclodextrin derivative in an ethanol/water solution, was used to functionalize support materials with a coat that is stable in aqueous solutions and which renders the coated materials hydrophilic. The functionalization proved to be controllable in terms of amount of cyclodextrin on the surface and can be implemented in existing production lines without investment in advanced production equipment. It is hypothesized that the cyclodextrins order themselves in structured layers forming channel‐like structures preserving the very large potential for uptake and release of active compounds that is known to cyclodextrins. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41047.     

Efficient wound odor removal by β‐cyclodextrin functionalized poly (ε‐caprolactone) nanofibers

Polymer‐cyclodextrin (CD) composite nanofibers, by virtue of the hollow cavities and abundant hydroxyl groups present in CDs, have tremendous potential in a variety of biomedical applications. However, in most cases, especially in aliphatic polyesters, polymer chains thread readily into CD cavities, therefore its potential has not yet been fully realized. Herein, we report the formation of poly(ε‐caprolactone) (PCL)/β‐CD functional nanofibers by electrospinning their mixture from chloroform/N,N‐dimethylformamide (60 : 40). The fiber diameters of the neat PCL and β‐CD functionalized fibers were measured from the images obtained from a scanning electron microscope and were found to be about 500 nm. The efficiency of wound odor absorbance by these composite fibers was studied using a simulated wound odor solution, consisting of butyric and propionic acids in ethanol. Immersion tests indicated that even under less than ideal test conditions, the nanofibers containing β‐CDs were very efficient in masking the odor. The odor masking capability of the β‐CD functionalized PCL nanofibers were further confirmed by thermogravimetric analyses and GC observations, with the former method showing unique degradation patterns. The PCL/β‐CD nanocomposites, by virtue of having their β‐CD cavities free and unthreaded by PCL, could potentially be an ideal substrate for removing wound odors through formation of inclusion compounds with odorants, while providing an ideal environment for the wound to heal. These results suggest tailoring polymer‐CD nanostructures for specific applications in wound odor absorbance, surface grafting of chemical moieties, and vehicles for drug delivery, as examples. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42782.