Synthesis of modified cyclic and acyclic dextrins and comparison of their complexation ability

• Kata Tuza,
• László Jicsinszky,
• Tamás Sohajda,
• István Puskás and
• Éva Fenyvesi

Beilstein J. Org. Chem. 2014, 10, 2836–2843, doi:10.3762/bjoc.10.301

• compared the complex forming ability of α-, β- and γ-cyclodextrins (α-CD, β-CD and γ-CD) with their open ring analogs. In addition to the native cyclodextrins also modified cyclodextrins and the corresponding maltooligomers, functionalized with neutral 2-hydroxypropyl moieties, were synthesized. A new

• -hydroxypropyl (HP) moieties, that are HP-α-CD, HP-β-CD, HP-γ-CD, HP-G6, HP-G7 and HP-G8 were synthesized and investigated as chiral additives for the separation of model compounds by CE. Results and Discussion We compared the complexing ability of the three native cyclodextrins and their acyclic analogs with CE

• only a slight difference was obtained (e.g., chrysantemic and camphoric acid with HP-β-CD/HP-G7) and an example was found when the open structure was superior to the closed one (chrysantemic acid with HP-γ-CD/HP-G8). With chlorpheniramine, CD derivatives yielded in all cases inevitably stronger

Thermal and oxidative stability of the Ocimum basilicum L. essential oil/β-cyclodextrin supramolecular system

• Daniel I. Hădărugă,
• Nicoleta G. Hădărugă,
• Corina I. Costescu,
• Ioan David and
• Alexandra T. Gruia

Beilstein J. Org. Chem. 2014, 10, 2809–2820, doi:10.3762/bjoc.10.298

• of α-(1→4)-linked glucopyranose units, which are obtained by starch degradation under controlled enzymatic conditions [36]. The most relevant natural CDs are α-, β-, and γ-CD, having six, seven, or eight glucopyranose moieties, but many other CD derivatives can be obtained in order to enhance their

Preparation and evaluation of cyclodextrin polypseudorotaxane with PEGylated liposome as a sustained release drug carrier

• Kayoko Hayashida,
• Taishi Higashi,
• Daichi Kono,
• Keiichi Motoyama,
• Koki Wada and
• Hidetoshi Arima

Beilstein J. Org. Chem. 2014, 10, 2756–2764, doi:10.3762/bjoc.10.292

• liposome and evaluate it as a sustained release drug carrier. PEGylated liposome encapsulating doxorubicin was disrupted by the addition of α-CD. Meanwhile, γ-CD included two PEG chains and/or one bending PEG chain of PEGylated liposome and formed PPRX without the disruption of the membrane integrity of

• the PEGylated liposome. Moreover, the release of doxorubicin and/or PEGylated liposome encapsulating doxorubicin from the PPRX was prolonged in accordance with the matrix type release mechanism. These findings suggest the potential of γ-CD PPRX as sustained release carriers for PEGylated liposome

• products. Keywords: cyclodextrins; doxorubicin; PEGylated liposome; polypseudorotaxane; sustained release; Introduction Cyclodextrins (CDs) are cyclic oligosaccharides comprising six (α-CD), seven (β-CD), and eight (γ-CD) glucopyranose units. They are characterized by a hydrophobic central cavity and a

Encapsulation of biocides by cyclodextrins: toward synergistic effects against pathogens

• Véronique Nardello-Rataj and
• Loïc Leclercq

Beilstein J. Org. Chem. 2014, 10, 2603–2622, doi:10.3762/bjoc.10.273

• degraded by the microorganism via mineralization. However, as pentachlorophenol also acts as a biocide, the fungal growth is inhibited and thereby, its own degradation as well. In 2006, to overcome this drawback, Boyle reported that addition of γ-CD can reduce the intrinsic toxicity of pentachlorophenol

• ). v) Reduction of the environmental toxicity The CDs can be used to minimize environmental pollution. As an example, in 1994, Loukas et al. reported the effect of γ-CD on dicyclopropylmethanone O-(diethoxyphosphoryl)oxime (named DCPE), a very active insecticide (Figure 4) [58]. The complexation of

• DCPE by the CD in aqueous solution was proved by 1H NMR. The stoichiometry of the DCPE–γ-CD complex was found to be 1:1 and the association constant was estimated at 1 488 M−1 at 35 °C. In the presence of 2.8 × 10−3 M of γ-CD, the stability of DCPE was enhanced by 2-fold. Moreover, the initial liquid

Host–guest-driven color change in water: influence of cyclodextrin on the structure of a copper complex of poly((4-hydroxy-3-(pyridin-3-yldiazenyl)phenethyl)methacrylamide-co-dimethylacrylamide)

• Nils Retzmann,
• Gero Maatz and
• Helmut Ritter

Beilstein J. Org. Chem. 2014, 10, 2480–2483, doi:10.3762/bjoc.10.259

• with N,N-dimethylacrylamide (6) using 2,2’-azobis(2,4-dimethyl)valeronitril (V-65) as an initiator (Scheme 1). The resulting copolymer 7 is orange colored. The color-changing effects of 7 upon addition of CuSO4 alone and in the presence of γ-CD were investigated and representative images are shown in

• Figure 1. The addition of CuSO4 to polymer 7 in a water/methanol mixture caused a color change from orange to red, which could be reversed by subsequent addition of γ-CD (Figure 1). Thus, we can anticipate a donor–acceptor-type bonding of the electron-rich azo dye with copper ions, that can be displaced

• by the addition of γ-CD [12]. Subsequent UV–vis spectroscopy allowed us to characterize the above mentioned color changes in the diluted state (Figure 2). Hereby a bathocromic shift of the peak maximum at 380 nm to 475 nm of 7 was observed due to complexation with CuSO4 which is reversible after γ-CD

Loose-fit polypseudorotaxanes constructed from γ-CDs and PHEMA-PPG-PEG-PPG-PHEMA

• Tao Kong,
• Lin Ye,
• Ai-ying Zhang and
• Zeng-guo Feng

Beilstein J. Org. Chem. 2014, 10, 2461–2469, doi:10.3762/bjoc.10.257

• analyses indicated that γ-CDs can accommodate and slip over PHEMA blocks to randomly distribute along the entire pentablock copolymer chain. This results in unique, single-chain stranded PPRs showing no characteristic channel-type crystal structure. Keywords: block copolymer; γ-CD; loose-fit; poly(2

• first PPRs (comprised of γ-CD and PEG) as early as the 1990s. The γ-CD-based PPRs with designated supramolecular structure have been seldom prepared as compared with the α-CD- or β-CD-based PPRs [5][6][7][8][9][10][11][12][13]. Besides the typical double-chain stranded PPR showing a characteristic

• channel-type crystal structure, as reported by Harada et al. [4], the so-called single-chain stranded γ-CD-based PPRs or PRs have recently attracted tremendous attention. Their potential smart material and biomedical applications stem from their unique loose-fit rather than tight-fit structure of γ-CDs

Effect of cyclodextrin complexation on phenylpropanoids’ solubility and antioxidant activity

• Miriana Kfoury,
• David Landy,
• Lizette Auezova,
• Hélène Greige-Gerges and
• Sophie Fourmentin

Beilstein J. Org. Chem. 2014, 10, 2322–2331, doi:10.3762/bjoc.10.241

• , stability, release and bioavailability of natural compounds [10][11][12][13]. CDs are a family of cyclic oligosaccharides obtained from enzymatic degradation of starch. The most common native CDs are α-cyclodextrin (α-CD), β-cyclodextrin (β-CD) and γ-cyclodextrin (γ-CD) composed of six, seven and eight (α

End group functionalization of poly(ethylene glycol) with phenolphthalein: towards star-shaped polymers based on supramolecular interactions

• Carolin Fleischmann,
• Hendrik Wöhlk and
• Helmut Ritter

Beilstein J. Org. Chem. 2014, 10, 2263–2269, doi:10.3762/bjoc.10.235

• combination of CRP with supramolecular complex formation, e.g., by the use of cyclodextrins (CDs) [6][7][34]. The most important representatives of these cyclic oligosaccharides with respect to industrial applications consist of six (α-CD), seven (β-CD) and eight (γ-CD) glucopyranose units and have a cone

The effect of permodified cyclodextrins encapsulation on the photophysical properties of a polyfluorene with randomly distributed electron-donor and rotaxane electron-acceptor units

• Aurica Farcas,
• Ana-Maria Resmerita,
• Pierre-Henri Aubert,
• Flavian Farcas,
• Iuliana Stoica and
• Anton Airinei

Beilstein J. Org. Chem. 2014, 10, 2145–2156, doi:10.3762/bjoc.10.222

• polyrotaxanes (4a and 4b), which consist of electron-accepting 9,9-dicyanomethylenefluorene 1 as an inclusion complex in persilylated β- or γ-cyclodextrin (TMS-β-CD, TMS-γ-CD) (1a, 1b) and methyltriphenylamine as an electron-donating molecule. They are statistically distributed into the conjugated chains of 9,9

• polyrotaxanes, which consist of 1a or 1b and 2 units statistically distributed into the conjugated chains of 3 and compared them with those of the corresponding 4 non-rotaxane counterpart (Figure 1). Results and Discussion To explore the effect of TMS-β-CD and TMS-γ-CD encapsulations toward native γ-CD on

• photophysical properties of PFs we performed the present study. TMS-β-CD and TMS-γ-CD macrocyclic molecules, 1 and 2 monomers, were prepared according to previously reported procedures [13][32][33][34][35]. The chemical structure of completely persilylated compounds was confirmed by using FTIR and NMR

A complete series of 6-deoxy-monosubstituted tetraalkylammonium derivatives of α-, β-, and γ-cyclodextrin with 1, 2, and 3 permanent positive charges

• Martin Popr,
• Simona Hybelbauerová and
• Jindřich Jindřich

Beilstein J. Org. Chem. 2014, 10, 1390–1396, doi:10.3762/bjoc.10.142

• -cyclodextrin (2) and 6I-O-p-toluenesulfonyl-γ-cyclodextrin (3) is flash column chromatography on a reverse phase C18 column with a step gradient. The use of this method allowed for the recovery of about 40% of the starting α- or γ-CD by flushing the column with 10% MeOH. Pure monotosylated product is then

• obtained after the elution with aqueous NH4OH, from a short column of strong cation exchanger in hydrogen form, in 70% and 74% yields, respectively. The derivative of γ-CD, compound 30, contained some trace amounts of impurities and needed to be further purified on a silica gel column. In the following

Oligomeric epoxide–amine adducts based on 2-amino-N-isopropylacetamide and α-amino-ε-caprolactam: Solubility in presence of cyclodextrin and curing properties

• Julian Fischer and
• Helmut Ritter

Beilstein J. Org. Chem. 2013, 9, 2803–2811, doi:10.3762/bjoc.9.315

• with hydrophobic guest molecules is widely used in drug, food, cosmetics, textile, adhesives, plastics and more industries [11][12][13]. Interestingly, recently it was confirmed that α- and β-CD cannot interact with PNIPAM. Only γ-CD has a tendency to include the PNIPAM main chain [14]. Normally, epoxy

Topochemical control of the photodimerization of aromatic compounds by γ-cyclodextrin thioethers in aqueous solution

• Hai Ming Wang and
• Gerhard Wenz

Beilstein J. Org. Chem. 2013, 9, 1858–1866, doi:10.3762/bjoc.9.217

• Hai Ming Wang Gerhard Wenz Organic Macromolecular Chemistry, Saarland University, Campus Saarbrücken C4 2, 66123 Saarbrücken, Germany 10.3762/bjoc.9.217 Abstract The formation of soluble 1:2 complexes within hydrophilic γ-cyclodextrin (γ-CD) thioethers allows to perform photodimerizations of

• aromatic guests under controlled, homogenous reaction conditions. The quantum yields for unsubstituted anthracene, acenaphthylene, and coumarin complexed in these γ-CD thioethers were found to be up to 10 times higher than in the non-complexed state. The configuration of the photoproduct reflected the

• undesirable heterogenous reaction conditions [19]. Yields of heterogenous photoreactions generally depend on the particle size of the educt phase because the penetration depth of the incident light is limited. Recently, we synthesized a series of highly water-soluble per-6-deoxy-thioethers of β- and γ-CD

Inclusion of the insecticide fenitrothion in dimethylated-β-cyclodextrin: unusual guest disorder in the solid state and efficient retardation of the hydrolysis rate of the complexed guest in alkaline solution

• Dyanne L. Cruickshank,
• Natalia M. Rougier,
• Raquel V. Vico,
• Susan A. Bourne,
• Elba I. Buján,
• Mino R. Caira and
• Rita H. de Rossi

Beilstein J. Org. Chem. 2013, 9, 106–117, doi:10.3762/bjoc.9.14

• solution containing 2% dioxane at 25 °C and in the presence of the native cyclodextrins α-CD, β-CD, γ-CD as well as the permethylated derivatives TRIMEA and TRIMEB, was performed [6]. This revealed weak host–guest association in the case of α-CD and insoluble complex formation in the case of the host

• TRIMEA [9], whereas for β-CD, γ-CD and TRIMEB the association constants for the inclusion complexes of 1 had the respective values 417, 99 and 511 M−1 [6], the hydrolytic decomposition of 1 being significantly retarded by all three CDs. The present study relates to the interaction between 1 and heptakis

Molecular solubilization of fullerene C₆₀ in water by γ-cyclodextrin thioethers

• Hai Ming Wang and
• Gerhard Wenz

Beilstein J. Org. Chem. 2012, 8, 1644–1651, doi:10.3762/bjoc.8.188

• of C60 in water reaching concentrations of 15 mg/L. Equilibrium state was approached after seven days without the use of organic cosolvents. The 1:2 stoichiometry of the C60/γ-CD thioether complexes was demonstrated by a parabolic phase-solubility diagram. In contrast, native γ-CD forms nanoparticles

• ][22]. CDs are cyclic oligosaccharides consisting of six, seven, eight or more glucose subunits connected through α-1,4 glycosidic linkages, called α-, β-, and γ-CD, respectively. CD molecules resemble truncated cones comprising a hydrophilic outer surface and a relatively hydrophobic cavity [23][24

• ][25]. CDs form water-soluble inclusion complexes with many hydrophobic or amphiphilic guest molecules [26], mainly driven by hydrophobic interactions [27]. Among the commercially available CDs, γ-CD with a clear width of d = 0.74 nm [28] is only large enough to partially accommodate C60, which has a

Synthesis and characterization of low-molecular-weight π-conjugated polymers covered by persilylated β-cyclodextrin

• Aurica Farcas,
• Ana-Maria Resmerita,
• Andreea Stefanache,
• Mihaela Balan and
• Valeria Harabagiu

Beilstein J. Org. Chem. 2012, 8, 1505–1514, doi:10.3762/bjoc.8.170

• photophysical properties of PFs by using persilylated γ-CD as a new host molecule [33]. Inclusion of bithiophene into persilylated β-cyclodextrin, randomly methylated β-cyclodextrin, or chemically modified CD derivatives, followed by copolymerization with fluorene monomers results in significant changes in the

Restructuring polymers via nanoconfinement and subsequent release

• Alan E. Tonelli

Beilstein J. Org. Chem. 2012, 8, 1318–1332, doi:10.3762/bjoc.8.151

• recently observed that PVAc coalesced from its IC formed with host urea (U) behaves quite similarly to PVAc coalesced from its γ-CD IC [72]. Coalesced semicrystalline polymers Poly(ε-caprolactone) (PCL) is a biodegradable/bioabsorbable aliphatic polyester that is often used in biomedical applications, such

• reorganize both morphologically and conformationally, either by formation of a crystalline inclusion complex (IC) between guest PET and host γ-cyclodextrin (γ-CD), followed by removal of the host γ-CD and coalescence of the guest PET (c-PET), or by precipitation (p-PET) from its solution in trifluoroacetic

• of ε-caprolactone with PPG-diol as the initiator [21]. In the IC of PCL-PPG-PCL formed with α-CD, only PCL blocks were included. In contrast, both PCL and PPG blocks were included in the IC of PCL-PPG-PCL formed with γ-CD, which has larger channels. Consequently, coalescence of the triblock copolymer

Interaction of cyclodextrins with pyrene-modified polyacrylamide in a mixed solvent of water and dimethyl sulfoxide as studied by steady-state fluorescence

• Akihito Hashidzume,
• Yongtai Zheng and
• Akira Harada

Beilstein J. Org. Chem. 2012, 8, 1312–1317, doi:10.3762/bjoc.8.150

• Gobancho, Chiyoda-ku, Tokyo 102-0076, Japan 10.3762/bjoc.8.150 Abstract The interaction of β- and γ-cyclodextrins (β-CD and γ-CD, respectively) with polyacrylamide modified with pyrenyl (Py) residues (pAAmPy) was investigated in a mixed solvent of water and dimethyl sulfoxide (DMSO) by steady-state

• fluorescence. In the absence of CD, the fluorescence spectra indicated that the formation of Py dimers became less favorable with increasing volume fraction of DMSO (xDMSO). The fluorescence spectra at varying xDMSO and CD concentrations indicated that β-CD and γ-CD included monomeric and dimeric Py residues

• , respectively. Using the fluorescence spectra, equilibrium constants of the formation of Py dimers and the complexation of β-CD and γ-CD with Py residues were roughly estimated based on simplified equilibrium schemes. Keywords: cyclodextrins; interaction; pyrene-modified polyacrylamide; steady-state

Cyclodextrin nanosponge-sensitized enantiodifferentiating photoisomerization of cyclooctene and 1,3-cyclooctadiene

• Wenting Liang,
• Cheng Yang,
• Masaki Nishijima,
• Gaku Fukuhara,
• Tadashi Mori,
• Andrea Mele,
• Franca Castiglione,
• Fabrizio Caldera,
• Francesco Trotta and
• Yoshihisa Inoue

Beilstein J. Org. Chem. 2012, 8, 1305–1311, doi:10.3762/bjoc.8.149

• very low temperatures (below −100 °C). Results and Discussion CDNSs 3, 4 and 5 were prepared in almost quantitative yields by reacting pyromellitic dianhydride (PDA) with β-CD or γ-CD in the presence of triethylamine in dimethyl sulfoxide at room temperature (Scheme 1) and purified by extensive Soxhlet

• convenient and also powerful tool for manipulating the stereochemical outcomes of supramolecular photochirogenesis. It should be noted that γ-CD-based nanosponge 5 gave the highest ee values for both 1E and 2EZ. This is in sharp contrast to the result reported for the photosensitization with conventional

• sensitizer-modified CDs [9][39], in which the more size-matched β-CD, rather than the larger-sized γ-CD, sensitizers consistently afforded 1E and 2EZ in (much) higher ee’s. This unusual behavior observed for β- and γ-CDNSs implies the operation of photosensitization and/or enantiodifferentiation mechanisms

Supramolecular FRET photocyclodimerization of anthracenecarboxylate with naphthalene-capped γ-cyclodextrin

• Qian Wang,
• Cheng Yang,
• Gaku Fukuhara,
• Tadashi Mori,
• Yu Liu and
• Yoshihisa Inoue

Beilstein J. Org. Chem. 2011, 7, 290–297, doi:10.3762/bjoc.7.38

• behavior of anthracenecarboxylate (AC) moieties. UV–vis, circular dichroism and fluorescence spectral studies revealed that two AC molecules are simultaneously included in the modified γ-CD cavity to form a right-handed screw and also that the naphthalene cap efficiently transfers the singlet energy to AC

• included in the CD cavity via the FRET mechanism. Compared to native γ-CD, the modified γ-CDs showed much higher first association constants (K1) but relatively lower second association constants (K2) for AC, leading to two-fold larger overall affinities (K1K2). Photocyclodimerization of AC with these

• modified γ-CDs produced more head-to-head (HH) dimers in much better enantiomeric excesses (ee) for anti-HH dimer compared to native γ-CD. Interestingly, FRET excitation further enhanced the chemical and optical yields of anti-HH dimer up to 36% and 35% ee, for which the highly efficient FRET sensitization