Cyanoethylation of the glucans dextran and pullulan: Substitution pattern and formation of nanostructures and entrapment of magnetic nanoparticles

• Kathrin Fiege,
• Heinrich Lünsdorf,
• Sevil Atarijabarzadeh and
• Petra Mischnick

Beilstein J. Org. Chem. 2012, 8, 551–566, doi:10.3762/bjoc.8.63

• when a solution of the polymer material is dialyzed against the poorer solvent water. A certain degree of hydrophobicity and amphiphilic balance is necessary to form stable particles [11][12][13][14]. We also observed nanostructure formation of alkynyldextrans [15]. Embedding magnetic iron cores in the

Amphiphilic dendritic peptides: Synthesis and behavior as an organogelator and liquid crystal

• Baoxiang Gao,
• Hongxia Li,
• Defang Xia,
• Sufang Sun and
• Xinwu Ba

Beilstein J. Org. Chem. 2011, 7, 198–203, doi:10.3762/bjoc.7.26

• Baoxiang Gao Hongxia Li Defang Xia Sufang Sun Xinwu Ba Key Laboratory of Medicinal Chemistry and Molecular Diagnosis, Ministry of Education, College of Chemistry and Environment Science, Hebei University, Baoding 071002, P.R. China 10.3762/bjoc.7.26 Abstract New amphiphilic dendritic peptides on

• dendritic polyaspartic acid were designed and synthesized. The organogel and liquid crystal properties of these amphiphilic dendritic peptides were fully studied by field-emission SEM, temperature dependent FT-IR, differential scanning calorimetry, polarization optical microscopy and X-ray diffraction

• experiments. Amphiphilic dendritic peptides G3 show good organogel properties with a minimum gelation concentration as low as 1 wt %. Furthermore, amphiphilic dendritic peptides G3 can form a hexagonal columnar liquid crystal assembly over a wide temperature range. Keywords: amphiphilic; dendritic peptides

Synthesis of cationic dibenzosemibullvalene-based phase-transfer catalysts by di-π-methane rearrangements of pyrrolinium-annelated dibenzobarrelene derivatives

• Heiko Ihmels and
• Jia Luo

Beilstein J. Org. Chem. 2011, 7, 119–126, doi:10.3762/bjoc.7.17

• amphiphilic tetraalkylammonium derivative that exhibits three different benzene-containing concave sites to which an organic substrate may associate by attractive van der Waals interactions or π-stacking. Moreover, additional functionalities, e.g., hydroxy or amino groups, may be attached to the benzene rings

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

• in direct miniemulsions with amphiphilic lipases (e.g., lipase-PSTM) [91]. Due to the very large interfacial area available, an apparent molecular weight as large as 200,000 g∙mol−1 could be obtained with full conversion of the monomer after 2 h. Another advantage of miniemulsion systems compared to

• locus is hydrophobic and spills out the water into the continuous phase. The ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide was used both as continuous phase and as stabilizer due to its amphiphilic properties. The approach is interesting for synthesizing polymers, which

Differences between β-Ala and Gly-Gly in the design of amino acids-based hydrogels

• Andreea Pasc,
• Firmin Obounou Akong,
• Sedat Cosgun and
• Christine Gérardin

Beilstein J. Org. Chem. 2010, 6, 973–977, doi:10.3762/bjoc.6.109

• complexing properties (AA = β-Ala or Gly–Gly) and iii) a flexible hydrophilic junction module, allowing for HLB control. Their synthesis is reported elsewere [11]. Gelation behaviour of amphiphiles In previous studies, we showed that amphiphilic compounds designed as AA-His-EO2-Cn, with n = 12, 14 and AA = β

• mechanism. On reducing the temperature to a certain value, amphiphilic molecules start to interact with each other by H-bonding to form micellar networks. The hydrophobicity of the 1D system is proportional to its length. Once the micellar fibre is too long, and thus too hydrophobic to be solubilised by

Oxalyl retro-peptide gelators. Synthesis, gelation properties and stereochemical effects

• Janja Makarević,
• Milan Jokić,
• Leo Frkanec,
• Vesna Čaplar,
• Nataša Šijaković Vujičić and
• Mladen Žinić

Beilstein J. Org. Chem. 2010, 6, 945–959, doi:10.3762/bjoc.6.106

• with lipophilic i-Bu groups and polar carboxylic acid or ester groups located on the opposite sides of the oxalamide plane resembling bola amphiphilic structures and those of (S,S)-diasteroisomers possessing the same groups located at both sides of the oxalamide plane. Such conformational

Pyridinium based amphiphilic hydrogelators as potential antibacterial agents

• Sayanti Brahmachari,
• Sisir Debnath,
• Sounak Dutta and
• Prasanta Kumar Das

Beilstein J. Org. Chem. 2010, 6, 859–868, doi:10.3762/bjoc.6.101

• rapid expansion of this field. In the present work we report the facile synthesis of amphiphilic hydrogelators having a quaternary pyridinium unit coupled to a hydrophobic long alkyl chain through an amide bond. Different amphiphiles with various hydrophobic chain length and polar head groups were

• rationally designed and synthesized to develop a structure-property relation. A judicious combination of hydrophilic and hydrophobic segments led to the development of pyridinium based amphiphilic hydrogelators having a minimum gelation concentration of 1.7%, w/v. Field emission scanning electronic

• originates from the interdigitated bilayer packing of the amphiphile leading to the development of an efficient hydrogel. Interestingly, the presence of the pyridinium scaffold along with the long alkyl chain render these amphiphiles inherently antibacterial. The amphiphilic hydrogelators exhibited high

Conjugated polymers containing diketopyrrolopyrrole units in the main chain

• Bernd Tieke,
• A. Raman Rabindranath,
• Kai Zhang and
• Yu Zhu

Beilstein J. Org. Chem. 2010, 6, 830–845, doi:10.3762/bjoc.6.92

• a strong fluorescence with maxima at 520 nm and a large Stokes-shift of 50 nm. However, due to the aliphatic structure of the main chain, the thermal stability was rather poor. Photoluminescent polyelectrolyte-surfactant complexes were obtained from an amphiphilic, unsymmetrically substituted DPP

Novel multi-responsive P2VP-block-PNIPAAm block copolymers via nitroxide-mediated radical polymerization

• Cathrin Corten,
• Katja Kretschmer and
• Dirk Kuckling

Beilstein J. Org. Chem. 2010, 6, 756–765, doi:10.3762/bjoc.6.89

• hydrophilic and hydrophobic groups in the polymer chains at the critical temperature. In order to prepare multi-responsive polymers, it is necessary to combine different kinds of monomers. For this purpose the preparation of defined block copolymers with different architectures is demanded. Amphiphilic or

• behavior was investigated in solution and on surfaces [23][24]. The synthesis of NIPAAm homopolymers through different controlled polymerization techniques is described in the literature. Using RAFT it was possible to obtain amphiphilic block copolymers of PNIPAAm (hydrophilic) and poly(styrene) (PS) or

• 2VP has been selected and the resulting polymer was used as a macroinitiator 2 (Scheme 1). Amphiphilic diblock copolymers undergo a self-assembly micellar process in solvents that are selective for one of the blocks [31]. By choosing selective conditions for each block, conventional micelles and so

RAFT polymers for protein recognition

• Alan F. Tominey,
• Julia Liese,
• Sun Wei,
• Klaus Kowski,
• Thomas Schrader and
• Arno Kraft

Beilstein J. Org. Chem. 2010, 6, No. 66, doi:10.3762/bjoc.6.66

• ]. Rotello and Thayumanavan have described amphiphilic polymer scaffolds, which nonspecifically bound to chymotrypsin, inhibited its peptidase activity and modulated substrate specificity; very high ionic strengths again released the protein from the polymer [6][7]. Protein recognition by multifunctional

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

• surfactants, are required to assure the colloidal stabilization of the polymer nanoparticles in aqueous medium. The properties of micelles (cmc, size and dynamics) depend on the chemical structures of amphiphilic copolymers. Macromolecular non-ionic surfactants appear to be the best suited from both the

• surfactants for mini-emulsion polymerization [5][6]. Amphiphilic block copolymers with pendant glucosamine units have been obtained by living cationic polymerization and their interaction with wheat germ agglutinin lectin investigated [7]. More recently, the synthesis of neoglycopolymers by living radical

• achieve interesting colloidal stabilization properties. Carbohydrate residues such as galactosyl moieties have also been incorporated as side groups through the ring opening of maleic anhydride based copolymers [10][11]. We recently reported the synthesis and characterization of amphiphilic copolymers

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

• . This indicates that the actual binding conformation of the bis-crown ether-diammonium ion aggregates may be more complex under the experimental conditions. Recently, they reported the application of a similar peptide forming an α-helical amphiphilic peptide nanostructure with cytolytic activity. A

Ring opening metathesis polymerization-derived block copolymers bearing chelating ligands: synthesis, metal immobilization and use in hydroformylation under micellar conditions

• Gajanan M. Pawar,
• Jochen Weckesser,
• Siegfried Blechert and
• Michael R. Buchmeiser

Beilstein J. Org. Chem. 2010, 6, No. 28, doi:10.3762/bjoc.6.28

• micellar catalytic set up are discussed. Keywords: block copolymers; catalysis; hydrophilic polymers; metathesis; micelles; Introduction Catalysts bound to amphiphilic block copolymers find increasing use in micellar catalysis since they combine the advantages of both homogeneous and heterogeneous

• N,N-dipyrid-2-ylacetamide and their use in hydroformylation reactions [9]. Here, we report on the immobilization of a Rh-N,N-dipyrid-2-ylacetamide-based catalyst on a soluble, amphiphilic, ring-opening metathesis polymerization- (ROMP) derived block copolymer and its use in hydroformylation [10

• catalysts covalently bound to amphiphilic polymers are used [2][4][29][30][31][32][33], have been reported to present suitable catalysts for numerous catalytic reactions. The hydroformylation under micellar conditions using catalysts bound to amphiphilic block copolymers was first reported by Nuyken et al