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

• granular morphology with a lower dispersity supported by a smaller roughness exponent compared with the non-rotaxane counterpart. Keywords: cyclodextrins; energy band gaps; fluorescence lifetimes; persilylated cyclodextrins; supramolecular encapsulation; surface morphology; Introduction Semiconducting π

• macrocycle molecules has been employed as an alternative approach to achieve the control of aggregation and to improve the photophysical and morphological characteristics [13]. In the past years, it has been demonstrated that the encapsulation of conjugated polymer into macrocycle cavities leads to an

• encapsulation of an acceptor monomer into CDs has been successfully employed for the fabrication of PFs materials with smaller optical and electrochemical band gaps [13]. Herein, we report on the synthesis as well as the characterization of the optical, electrochemical and morphological properties of 4a and 4b

Carbohydrate PEGylation, an approach to improve pharmacological potency

• M. Eugenia Giorgi,
• Rosalía Agusti and
• Rosa M. de Lederkremer

Beilstein J. Org. Chem. 2014, 10, 1433–1444, doi:10.3762/bjoc.10.147

• of two hydroxy methylene groups present in pentofuranose derivatives with a PEG dimethyl ester yielded sugar-PEG copolymers used for drug encapsulation. The carbohydrate monomer was obtained by a multistep synthesis starting from the easily available diacetone glucose (Scheme 5) [41]. Galactose has

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

• , respectively. The most commonly utilized feature of native CDs is their ability to form noncovalent inclusion complexes with a wide range of guest molecules [2]. In the majority of industrial applications, natural CDs serve as encapsulation agents with a high affinity toward suitable lipophilic organic guests

Staudinger ligation towards cyclodextrin dimers in aqueous/organic media. Synthesis, conformations and guest-encapsulation ability

• Malamatenia D. Manouilidou,
• Yannis G. Lazarou,
• Irene M. Mavridis and
• Konstantina Yannakopoulou

Beilstein J. Org. Chem. 2014, 10, 774–783, doi:10.3762/bjoc.10.73

• , were found to adopt closed conformations by intramolecular self-inclusion. On the other hand, association via intermolecular binding was also observed in aqueous solution, confirmed by DOSY NMR experiments. Despite self-inclusion, the β-CD cavities were capable of guest encapsulation, as shown by

• environment, rigid spacer/linker), have not been explored so far toward formation of CD dimers. For any realistic application of CD oligomers, especially for drug encapsulation, some key requirements can be set: (i) ease of preparation, (ii) efficient purification, (iii) aqueous solubility of the oligomer

Thermodynamically stable [4 + 2] cycloadducts of lanthanum-encapsulated endohedral metallofullerenes

• Yuta Takano,
• Yuki Nagashima,
• M. Ángeles Herranz,
• Nazario Martín and
• Takeshi Akasaka

Beilstein J. Org. Chem. 2014, 10, 714–721, doi:10.3762/bjoc.10.65

• ]. The encapsulation results in the electron transfer from metal atoms to the fullerene cage, which leads to unique electronic, magnetic, and chemical properties for EMFs that cannot be expected for empty fullerenes. Due to the numerous electronic properties EMFs are anticipated as promising materials in

Structure elucidation of β-cyclodextrin–xylazine complex by a combination of quantitative ¹H–¹H ROESY and molecular dynamics studies

• Syed Mashhood Ali,
• Kehkeshan Fatma and
• Snehal Dhokale

Beilstein J. Org. Chem. 2013, 9, 1917–1924, doi:10.3762/bjoc.9.226

• the cavity is hydrophobic [2][3]. The encapsulation of a guest into the CD cavity has a profound effect on the chemical, physical and biological properties of the guest. The structure establishment of CD inclusion complexes in solution state is a challenging task considering the fact that the

Polymeric redox-responsive delivery systems bearing ammonium salts cross-linked via disulfides

• Christian Dollendorf,
• Martin Hetzer and
• Helmut Ritter

Beilstein J. Org. Chem. 2013, 9, 1652–1662, doi:10.3762/bjoc.9.189

• of DNA encapsulation used in anti-cancer treatment [16][17][18][19][20][21][22][23]. Further examples for polymeric networks based on poly(ethylenimine) (PEI) or poly(diethyl acrylamide) (PDEA) can be found in the literature [24][25][26]. Disulfide bonds are generally stable in human blood

Spin state switching in iron coordination compounds

• Philipp Gütlich,
• Ana B. Gaspar and
• Yann Garcia

Beilstein J. Org. Chem. 2013, 9, 342–391, doi:10.3762/bjoc.9.39

Theoretical study on β-cyclodextrin inclusion complexes with propiconazole and protonated propiconazole

• Adrian Fifere,
• Narcisa Marangoci,
• Stelian Maier,
• Adina Coroaba,
• Dan Maftei and
• Mariana Pinteala

Beilstein J. Org. Chem. 2012, 8, 2191–2201, doi:10.3762/bjoc.8.247

• , “Gheorghe Asachi” Technical University of Iasi, 700050 Iasi, Romania Faculty of Chemistry, “Al. I. Cuza” University Iasi, Iasi 700506, Romania 10.3762/bjoc.8.247 Abstract The synthesis of the β-cyclodextrin/propiconazole nitrate inclusion complex and the advantages of the encapsulation of this drug were

Cyclodextrin-based nanosponges as drug carriers

• Francesco Trotta,
• Marco Zanetti and
• Roberta Cavalli

Beilstein J. Org. Chem. 2012, 8, 2091–2099, doi:10.3762/bjoc.8.235

• suspension of β-CD nanosponges [34]. Encapsulation of tamoxifen in these nanosponges was more than 40% w/w, since 5 mg of nanosponges can solubilise 2.2 mg of tamoxifen. The in vitro release of tamoxifen from nanosponges showed pseudo-zero order kinetics. After 2 h about 60% of the encapsulated drug had been

• proposed as a sustained drug-delivery system for oral administration. Acyclovir is a medium polarity drug with a solubility in water of 1.5 mg/mL. Special carboxylated nanosponges, containing dissociable carboxylic groups in their structure were developed for its encapsulation. They represent a further

• electrostatic contribution for drug encapsulation, in addition to the cyclodextrin cavities. Electrostatic interactions may occur between the carboxylic groups present in the nanosponge structure and the amino group of acyclovir. In vitro, acyclovir-loaded carboxylated nanosponges [39] showed prolonged release

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

• chemical structure and the thermal and morphological properties of the resulting polyrotaxane were investigated by using NMR and FT-IR spectroscopy, TGA, DSC and AFM analysis. The encapsulation of BT inside the PS-βCD cavity results in improvements in the solubility, as well as in different surface

• interactions; bulky groups (also known as stoppers) are attached at the ends of the axle to prevent dethreading of the host. In the past few years many authors have demonstrated that the encapsulation of conjugated polymers into macrocycle cavities plays an important role in the construction of diverse

Synthesis and anion recognition properties of shape-persistent binaphthyl-containing chiral macrocyclic amides

• Marco Caricato,
• Nerea Jordana Leza,
• Claudia Gargiulli,
• Giuseppe Gattuso,
• Daniele Dondi and
• Dario Pasini

Beilstein J. Org. Chem. 2012, 8, 967–976, doi:10.3762/bjoc.8.109

• loss of the initial symmetry. From the preliminary data in our hands, it is clear that there is a slow-exchanging equilibrium on the NMR time scale: the bulkier acetoxy group presumably inhibits a binding mechanism based on a fast host–guest exchange. A slow encapsulation mechanism, with multiple modes

On the mechanism of action of gated molecular baskets: The synchronicity of the revolving motion of gates and in/out trafficking of guests

• Keith Hermann,
• Stephen Rieth,
• Hashem A. Taha,
• Bao-Yu Wang,
• Christopher M. Hadad and
• Jovica D. Badjić

Beilstein J. Org. Chem. 2012, 8, 90–99, doi:10.3762/bjoc.8.9

• thermodynamics of CH3CCl3 (2) entering and leaving the gated molecular basket 1. We found that the encapsulation is first-order in basket 1 and guest 2, while the decomplexation is zeroth-order in the guest. Importantly, the interchange mechanism in which a molecule of CH3CCl3 directly displaces the entrapped

• CH3CCl3 was not observed. Furthermore, the examination of the additivity of free energies characterizing the encapsulation process led to us to deduce that the revolving motion of the gates and in/out trafficking of guests is synchronized, yet still a function of the affinity of the guest for occupying

• the basket: Specifically, the greater the affinity of the guest for occupying the basket, the less effective the gates are in “sweeping” the guest as the gates undergo their revolving motion. Keywords: dynamic NMR; host–guest chemistry; linear free-energy relationships; molecular encapsulation

Supramolecular chemistry II

• Christoph A. Schalley

Beilstein J. Org. Chem. 2011, 7, 1541–1542, doi:10.3762/bjoc.7.181

• Beilstein Journal of Organic Chemistry [1]. This first series of articles had quite a broad scope ranging from encapsulation and carbohydrate, peptide, anion and ammonium ion binding, through chiral recognition, the formation of pseudorotaxanes and template effects, all the way to allosteric binding to

Hyperbranched polyethylenimine bearing cyclodextrin moieties showing temperature and pH controlled dye release

• Indra Böhm,
• Susanne Katharina Kreth and
• Helmut Ritter

Beilstein J. Org. Chem. 2011, 7, 1130–1134, doi:10.3762/bjoc.7.130

• -adamantylaminoanthraquinone (AQ-Ada) were encapsulated by the cavity of CD modified PEI. Due to these different types of interaction, the dyes can be controllably released from the CD-cavity (AQ-Ada) by temperature variation or from salt encapsulation by pH variation (AQ-OH), as monitored by UV–vis spectroscopy. Keywords

Olefin metathesis in nano-sized systems

• Didier Astruc,
• Abdou K. Diallo,
• Sylvain Gatard,
• Liyuan Liang,
• Cátia Ornelas,
• Victor Martinez,
• Denise Méry and
• Jaime Ruiz

Beilstein J. Org. Chem. 2011, 7, 94–103, doi:10.3762/bjoc.7.13

• ) or, more usefully, dendrimer encapsulation – ring closing metathesis (RCM), cross metathesis (CM), enyne metathesis reactions (EYM) – for reactions in water without a co-solvent and (ii) construction and functionalization of dendrimers by CM reactions. Keywords: dendrimer; green chemistry

• reactions. This strongly argues in favor of dendritic protection (probably by encapsulation) of the reactive species. RCM reactions need less catalyst 7 in organic solvents [1] than in the presence of water, especially in the absence of the dendrimer 11. Thus the hydrophobic dendrimer interior should indeed

Miniemulsion polymerization as a versatile tool for the synthesis of functionalized polymers

• Daniel Crespy and
• Katharina Landfester

Beilstein J. Org. Chem. 2010, 6, 1132–1148, doi:10.3762/bjoc.6.130

• the encapsulation of hydrophobic substances could be obtained. Capsules could be also obtained when methacrylic acid was used instead of acrylic acid [31]. Wu and Schork investigated the copolymerization between the functional n-methylol acrylamide and vinyl acetate in batch and semi-batch processes

• reported by Musyanovych and Landfester for the polymerization of n-butyl cyanoacrylate [90]. The monomer was solubilized in the continuous phase and the polymer precipitated during the polymerization at the interface of aqueous droplets. The process could be successfully used for the encapsulation of DNA

• with an encapsulation efficiency of almost 100%. The method is particularly interesting since it allows the encapsulation of hydrophilic substances in the polymer capsules. The “classical” miniemulsions described above are, however, limited to particular monomers for anionic polymerization. In fact in

Design and synthesis of a cyclitol-derived scaffold with axial pyridyl appendages and its encapsulation of the silver(I) cation

• Pierre-Marc Léo,
• Christophe Morin and
• Christian Philouze

Beilstein J. Org. Chem. 2010, 6, 1022–1024, doi:10.3762/bjoc.6.115

Hybrid biofunctional nanostructures as stimuli-responsive catalytic systems

• Gernot U. Marten,
• Thorsten Gelbrich and
• Annette M. Schmidt

Beilstein J. Org. Chem. 2010, 6, 922–931, doi:10.3762/bjoc.6.98

• response. Thus the agglomerated particles can be separated easily by low magnetic field gradients, and facilitate, for instance, the separation process in purification applications of biomolecules. Reversible thermoflocculation of magnetic colloids by encapsulation with thermoresponsive polymers has been

Poly(glycolide) multi-arm star polymers: Improved solubility via limited arm length

• Florian K. Wolf,
• Anna M. Fischer and
• Holger Frey

Beilstein J. Org. Chem. 2010, 6, No. 67, doi:10.3762/bjoc.6.67

• environment when core–shell topologies for encapsulation are desired. Here we present a solvent-free synthetic strategy for multi-arm star block copolymers with a hyperbranched polyether core and PGA arms, systematically varying arm length. The combination of glycolide with a multifunctional initiator studied

New amphiphilic glycopolymers by click functionalization of random copolymers – application to the colloidal stabilisation of polymer nanoparticles and their interaction with concanavalin A lectin

• Otman Otman,
• Paul Boullanger,
• Eric Drockenmuller and
• Thierry Hamaide

Beilstein J. Org. Chem. 2010, 6, No. 58, doi:10.3762/bjoc.6.58

• combine immediate and delayed effects, through the selection of an efficient drug and the design of a suitable dosage form. Encapsulation of hydrophobic substances in aqueous dispersed media can be performed by a number of methods. Notably, synthetic polymer-based nanoparticles have received considerable

Molecular recognition of organic ammonium ions in solution using synthetic receptors

• Andreas Späth and
• Burkhard König

Beilstein J. Org. Chem. 2010, 6, No. 32, doi:10.3762/bjoc.6.32

• encapsulation [116] (Figure 7). On inclusion in the cavity of the cryptand, the guest is shielded by three or more polyether bridges. As a result of this encapsulation, cryptands form more stable complexes than coronands (Ka = 106 for NH4+ in methanol at 25 °C). In addition, solution thermodynamics of amino

Size selective recognition of small esters by a negative allosteric hemicarcerand

• Holger Staats and
• Arne Lützen

Beilstein J. Org. Chem. 2010, 6, No. 10, doi:10.3762/bjoc.6.10

• Molecular mechanics studies (MMFF force field, Spartan 08) indicate that 2 offers only a very small cavity surrounded by rather non-polar acetal and aryl groups for the encapsulation of a small non-polar substrate via dispersive interactions. Unfortunately, 2 is soluble only in rather non-polar solvents

• substrates with the solvent for the encapsulation we chose to do the binding studies in mesitylene-d12 which seemed to be too large to fit into the cavity of 2. We then chose to test its ability to bind to simple esters like ethyl acetate (3), n-propyl propionate (4), n-butyl butyrate (5), isopropyl

• hydrogen atoms of the acetal bridges of the resorcinarenes (4.2–4.8 and 5.3–5.9 ppm) and of the bipyridine (7.5–8.0 ppm), respectively. Note that these hydrogen atoms are all located more or less inside the cavity which clearly indicates encapsulation of the esters rather than a kind of accidental binding

Control of stilbene conformation and fluorescence in self-assembled capsules

• Mark R. Ams,
• Dariush Ajami,
• Stephen L. Craig,
• Jye-Shane Yang and
• Julius Rebek Jr

Beilstein J. Org. Chem. 2009, 5, No. 79, doi:10.3762/bjoc.5.79

• : molecular twisting; quenching; reversible encapsulation; self-assembly; stilbene fluorescence; Introduction The fluorescence of trans-stilbene has been extensively researched [1], and weak fluorescence occurs in aqueous solutions or typical organic solvents. In a highly structured environment such as an

• host. The homologue, 4-ethyl-4′-methylstilbene (3), is also encapsulated (see Supporting Information File 1 for NMR spectrum), but the slightly longer 4,4′-diethyl derivative 4 simply does not fit. Figure 2 illustrates the effect of encapsulation on 3 (assembly 6). The fluorescence is 96% quenched when

Coaxial electrospinning of liquid crystal-containing poly(vinylpyrrolidone) microfibres

• Eva Enz,
• Ute Baumeister and
• Jan Lagerwall

Beilstein J. Org. Chem. 2009, 5, No. 58, doi:10.3762/bjoc.5.58

• (vinylpyrrolidone) with the liquid crystal 4-cyano-4′-octylbiphenyl in its smectic phase as core material could be produced. The encapsulation leads to remarkable confinement effects on the liquid crystal, inducing changes in its phase sequence. We conducted a series of experiments to determine the effect of