Synthesis and photophysical characteristics of polyfluorene polyrotaxanes

• Aurica Farcas,
• Giulia Tregnago,
• Ana-Maria Resmerita,
• Pierre-Henri Aubert and
• Franco Cacialli

Beilstein J. Org. Chem. 2015, 11, 2677–2688, doi:10.3762/bjoc.11.288

• filtered, dried and purified by Soxhlet extraction with methanol and acetone in succession to remove the oligomers. The polymer was further purified by reprecipitation from concentrated CHCl3 solution with methanol, collected by centrifugation and vacuum dried at 60 °C to afford 3·TM-βCD (128 mg, 18.8

Assembly of synthetic Aβ miniamyloids on polyol templates

• Sebastian Nils Fischer and
• Armin Geyer

Beilstein J. Org. Chem. 2015, 11, 2646–2653, doi:10.3762/bjoc.11.284

• are known to form fibrils and there is no way to stop the process until complete precipitation. Intermediate soluble oligomers were identified as neurotoxic agents, but they are difficult to study because of their heterogeneous composition and transient character due to the onset of amyloid formation

• (Figure 1) [4]. Based on the concept of the existence of toxic Aβ oligomers, we recently developed covalently linked dimers of Aβ epitopes – so called synthetic Aβ miniamyloids – and successfully characterized their neurotoxicity [5]. These oligomeric peptides do not show an unmitigated fibrillation. The

• dimeric Aβ(28–40) epitopes exhibit reversible folding and show avidity towards the conformation-specific nAbsAβ, the antibody which selectively binds and eliminates toxic Aβ oligomers but neither binds Aβ monomers or fibrils. The Aβ(28–40) epitopes were irreversibly linked at their carboxy-terminal ends

Aggregation behaviour of amphiphilic cyclodextrins: the nucleation stage by atomistic molecular dynamics simulations

• Giuseppina Raffaini,
• Antonino Mazzaglia and
• Fabio Ganazzoli

Beilstein J. Org. Chem. 2015, 11, 2459–2473, doi:10.3762/bjoc.11.267

• modulates the formation of micelles, vesicles, nanospheres (or dense aggregates), and nanocapsules [1]. In particular, non-ionic aCD obtained from β-CD modified with hydrophobic thioalkyl chains (H groups in the following) at the primary rim and short polar PEG oligomers (P groups) at the secondary rim form

Supramolecular chemistry: from aromatic foldamers to solution-phase supramolecular organic frameworks

• Zhan-Ting Li

Beilstein J. Org. Chem. 2015, 11, 2057–2071, doi:10.3762/bjoc.11.222

• acetonitrile. The stability of the complexes increased with the elongation of the ethylene glycol chains. Aromatic amide oligomers: extended secondary structures. Our students also tried to make use of hydrogen bonding to control the conformation of aromatic amide backbones. Previously, Hamilton [26], Gong [27

• Technology, reported the formation of straight conformations by oligomers 13a,b and 14, which was driven by successive intramolecular hydrogen bonding [31] (Scheme 7), whereas Jiang Zhu, who is currently an associate professor at North Sichuan Medical College, described the zigzag conformation of oligomers

• 15a–d, which is also stabilized by intramolecular hydrogen bonding [32] (Scheme 7). The aromatic units in oligomers 13–15 can be easily combined into one sequence. By changing their number and position, sequences of different length and shape or in a controlled conformation can be designed [33][34

Efficient synthesis of π-conjugated molecules incorporating fluorinated phenylene units through palladium-catalyzed iterative C(sp²)–H bond arylations

• Fatiha Abdelmalek,
• Fazia Derridj,
• Safia Djebbar,
• Jean-François Soulé and
• Henri Doucet

Beilstein J. Org. Chem. 2015, 11, 2012–2020, doi:10.3762/bjoc.11.218

• , 15000 Tizi-Ouzou, Algeria Laboratoire d’hydrométallurgie et chimie inorganique moléculaire, Faculté de Chimie, U.S.T.H.B. Bab-Ezzouar, Algeria 10.3762/bjoc.11.218 Abstract We report herein a two or three step synthesis of fluorinated π-conjugated oligomers through iterative C–H bond arylations

• regioselective activation of C(sp2)–H bonds. Keywords: catalysis; C–H bond arylations; desulfitative; fluorine; palladium; Introduction Fluorinated π-conjugated oligomers increasingly receive recent interest owing to their particular applications as electronic devices (e.g., in organic solar cells) [1][2][3][4

• oligomers have unique π-staking arrangement resulting sometimes in specific electronic properties [3]. Hence, a practical method for the synthesis of fluorinated π-conjugated oligomers that will use the specificity of fluorine atoms is highly desirable for the chemist community. Palladium-catalyzed cross

Stereochemistry of ring-opening/cross metathesis reactions of exo- and endo-7-oxabicyclo[2.2.1]hept-5-ene-2-carbonitriles with allyl alcohol and allyl acetate

• Piotr Wałejko,
• Michał Dąbrowski,
• Lech Szczepaniak,
• Jacek W. Morzycki and
• Stanisław Witkowski

Beilstein J. Org. Chem. 2015, 11, 1893–1901, doi:10.3762/bjoc.11.204

• resulted mixtures were easier to work-up and to separate from ROMP oligomers by simple filtration (see Figure 2). A different isomeric products distribution was observed in the mixtures of type A products (1-2 and 1-3). In reactions of exo- and endo-norbornene 1 and 2, with the acetate 3, approximately a

Robust bifunctional aluminium–salen catalysts for the preparation of cyclic carbonates from carbon dioxide and epoxides

• Yuri A. Rulev,
• Zalina Gugkaeva,
• Victor I. Maleev,
• Michael North and
• Yuri N. Belokon

Beilstein J. Org. Chem. 2015, 11, 1614–1623, doi:10.3762/bjoc.11.176

• the polycarbonate consisted of a mixture of oligomers with a range of monomer units (n from 4 to 10) with the maximum intensity at n = 6. Both ends of the polymer chain are capped with alcohol groups, suggesting that chain-transfer to adventitious moisture occurred during the polymerisation. GPC data

Star-shaped tetrathiafulvalene oligomers towards the construction of conducting supramolecular assembly

• Masahiko Iyoda and
• Masashi Hasegawa

Beilstein J. Org. Chem. 2015, 11, 1596–1613, doi:10.3762/bjoc.11.175

• 10.3762/bjoc.11.175 Abstract The construction of redox-active supramolecular assemblies based on star-shaped and radially expanded tetrathiafulvalene (TTF) oligomers with divergent and extended conjugation is summarized. Star-shaped TTF oligomers easily self-aggregate with a nanophase separation to

• produce supramolecular structures, and their TTF units stack face-to-face to form columnar structures using the fastener effect. Based on redox-active self-organizing supramolecular structures, conducting nanoobjects are constructed by doping of TTF oligomers with oxidants after the formation of such

• nanostructures. Although radical cations derived from TTF oligomers strongly interact in solution to produce a mixed-valence dimer and π-dimer, it seems to be difficult to produce nanoobjects of radical cations different from those of neutral TTF oligomers. In some cases, however, radical cations form

Dicarboxylic esters: Useful tools for the biocatalyzed synthesis of hybrid compounds and polymers

• Ivan Bassanini,
• Karl Hult and
• Sergio Riva

Beilstein J. Org. Chem. 2015, 11, 1583–1595, doi:10.3762/bjoc.11.174

• beginning of the use of lipases in organic solvents. In 1984 Okumura et al. [48] produced oligomers of several dicarboxylic acids (C6 to C14) in combination with several diols (C2 and C3). Since then the use of lipase-catalyzed preparation of polymers has grow very much and has been reviewed many times (see

• oligomers followed by a second step at higher temperature and/or lower pressure. The synthesis of oligomers and short telechelics (oligomers with functionalized ends) avoids much of the problems and afford better reaction rates. Yang et al. polymerized ethyl glycolate with diethyl sebacate and 1,4-butandiol

• obtaining high molecular weight polyesters by lipase catalysis. This problem can be circumvented by the synthesis of telechelics, oligomers with functional ends. The synthesis of oligomers avoids the precipitation of polymers during the synthesis. The functional ends of the telechelics can be used in a

Thermal properties of ruthenium alkylidene-polymerized dicyclopentadiene

• Yuval Vidavsky,
• Yotam Navon,
• Yakov Ginzburg,
• Moshe Gottlieb and
• N. Gabriel Lemcoff

Beilstein J. Org. Chem. 2015, 11, 1469–1474, doi:10.3762/bjoc.11.159

• equilibrates and further ruthenium–alkylidene metathesis with neighboring double bonds may be promoted. Alternatively, thermal decomposition of DCPD (or larger oligomers) to cyclopentadiene (CPD) by a retro-Diels–Alder reaction could also explain the observed phenomenon, although unlikely at room temperature

New tris- and pentakis-fused donors containing extended tetrathiafulvalenes: New positive electrode materials for rechargeable batteries

• Shintaro Iwamoto,
• Yuu Inatomi,
• Daisuke Ogi,
• Satoshi Shibayama,
• Yukiko Murakami,
• Minami Kato,
• Kazuyuki Takahashi,
• Kazuyoshi Tanaka,
• Nobuhiko Hojo and
• Yohji Misaki

Beilstein J. Org. Chem. 2015, 11, 1136–1147, doi:10.3762/bjoc.11.128

• attention as potential components for organic functional materials as well as multi-electron redox systems [1][2][3][4][5]. Fused TTF oligomers [5] are of considerable interest as multi-electron redox systems, because the TTF units strongly interact with each other. For example, a bis-fused TTF, 2,5-bis(1,3

• , insertion of a linkage group, which is usually required to construct polymers, also results in considerable decrease in the theoretical capacity [13]. As for fused TTF oligomers, theoretical capacity rather increases as the number of TTF units increases because two carbons are shared in the two TTF units

• TTF oligomers, because thiophene inserted precursors are more soluble than the TTF-type precursors as mentioned above. We succeeded in the synthesis of fused TTF pentamer and heptamer composed of the unit of 4 [20]. In this paper, we report the synthesis and electrochemical properties of vinyl

Advances in the synthesis of functionalised pyrrolotetrathiafulvalenes

• Luke J. O’Driscoll,
• Sissel S. Andersen,
• Marta V. Solano,
• Dan Bendixen,
• Morten Jensen,
• Troels Duedal,
• Jess Lycoops,
• Cornelia van der Pol,
• Rebecca E. Sørensen,
• Karina R. Larsen,
• Kenneth Myntman,
• Christian Henriksen,
• Stinne W. Hansen and
• Jan O. Jeppesen

Beilstein J. Org. Chem. 2015, 11, 1112–1122, doi:10.3762/bjoc.11.125

• complex alkylating agents can be successfully used in place of methyl iodide. For example, functionalised ethylene glycol oligomers have been used in the preparation of rotaxanes and pseudorotaxanes [28][41][42][45]. Although CsOH·H2O is most commonly used, other bases are also known to remove the

Quarternization of 3-azido-1-propyne oligomers obtained by copper(I)-catalyzed azide–alkyne cycloaddition polymerization

• Shun Nakano,
• Akihito Hashidzume and
• Takahiro Sato

Beilstein J. Org. Chem. 2015, 11, 1037–1042, doi:10.3762/bjoc.11.116

• –alkyne cycloaddition (CuAAC) polymerization, were quarternized quantitatively with methyl iodide in sulfolane at 60 °C to obtain soluble oligomers. The conformation of the quarternized oligoAP in dilute DMSO-d6 solution was examined by pulse-field-gradient spin-echo NMR based on the touched bead model

• using methyl iodide to obtain soluble oligomers; oligoAP was quarternized quantitatively with a large excess of methyl iodide in sulfolane at 60 °C. The oligoAPMe of xq = 0.94 was soluble in DMSO, indicating that quarternization makes the oligoAP soluble. The 1H and 13C NMR spectra for the oligoAPMe

Interactions between tetrathiafulvalene units in dimeric structures – the influence of cyclic cores

• Huixin Jiang,
• Virginia Mazzanti,
• Christian R. Parker,
• Søren Lindbæk Broman,
• Jens Heide Wallberg,
• Karol Lušpai,
• Adam Brincko,
• Henrik G. Kjaergaard,
• Anders Kadziola,
• Peter Rapta,
• Ole Hammerich and
• Mogens Brøndsted Nielsen

Beilstein J. Org. Chem. 2015, 11, 930–948, doi:10.3762/bjoc.11.104

• in the concentrated and in the diluted solutions. This suggests that the doubly charged structures 4 and 5 are in the form of a spinless dication, represented by the two interacting intrachain polarons. Obviously, the optical spectra of interchain π-dimers of short oligomers are characterized by two

Impact of multivalent charge presentation on peptide–nanoparticle aggregation

• Daniel Schöne,
• Boris Schade,
• Christoph Böttcher and
• Beate Koksch

Beilstein J. Org. Chem. 2015, 11, 792–803, doi:10.3762/bjoc.11.89

• and even the binding constant of R2A3 is slightly higher. Therefore it can be assumed that the fiber formation increases the binding constant significantly (Table 1). Compared to coiled-coil oligomers the α-helical peptide fiber has a highly ordered structure and the charge density is well localized

Discrete multiporphyrin pseudorotaxane assemblies from di- and tetravalent porphyrin building blocks

• Mirko Lohse,
• Larissa K. S. von Krbek,
• Sebastian Radunz,
• Suresh Moorthy,
• Christoph A. Schalley and
• Stefan Hecht

Beilstein J. Org. Chem. 2015, 11, 748–762, doi:10.3762/bjoc.11.85

• detected but with very low intensity. This partly bound species A2@C4 could in principle allow formation of small oligomers, if present in solution. The fact that no oligomers could be detected and the very small abundance of the signal of the partly bound state [Na2A2@C4]4+ (m/z = 873) leads to the

• are again only traces of the possible 1:1 pseudorotaxane [A4@C2]4+ (m/z = 825) detected (Figure 10c,d). As mentioned above, this is most probably a product of the ionization process. The free hosts C4 and C2 are detected in only small amounts or traces. Again, in both cases no oligomers are observed

Probing multivalency in ligand–receptor-mediated adhesion of soft, biomimetic interfaces

• Stephan Schmidt,
• Hanqing Wang,
• Daniel Pussak,
• Simone Mosca and
• Laura Hartmann

Beilstein J. Org. Chem. 2015, 11, 720–729, doi:10.3762/bjoc.11.82

• ligands are typically oligomers consisting of multiple subunits of varying complexity. When binding to receptors this leads to a receptor clustering or so-called glycocluster effect. However, multivalency even goes further: For example when cells form contact layers of surface anchored carbohydrates the

• , because a potentially multivalent arrangement of mannose on AA and CA grafting units could lead to chelate- or subsite binding at the ConA receptor enhancing the affinity of individual mannose units. In contrast to other work on similar multivalent scaffolds like oligomers, dendrimers or nanoparticles [20

DNA display of glycoconjugates to emulate oligomeric interactions of glycans

• Alexandre Novoa and
• Nicolas Winssinger

Beilstein J. Org. Chem. 2015, 11, 707–719, doi:10.3762/bjoc.11.81

• hybridization instructions (Figure 1). This hybridization can be used to rigidify a nucleic acid strand containing multiple glycans at variable positions, to generate oligomers through half-slide hybridization and to combinatorial pair multiple ligands. The flexibility of the template can be further tuned with

• ]. Three galactosylated DNA conjugates with different lengths were obtained and mixed with the corresponding half-slide complementary DNA to obtain supramolecular oligomers forming galactoside clusters. The different assemblies were tested for their binding affinity to the RCA120 lectin showing a

Self-assembly of heteroleptic dinuclear metallosupramolecular kites from multivalent ligands via social self-sorting

• Christian Benkhäuser and
• Arne Lützen

Beilstein J. Org. Chem. 2015, 11, 693–700, doi:10.3762/bjoc.11.79

• signals (e.g., around 9.8, 7.5, and 5.3 ppm) which might indicate that some minor amounts of oligomers/polymers are still existing. However, the intensity of these signals was so low, that we could not assign a diffusion coefficient to them in a 2D-DOSY experiment to corroborate this assumption

Synthesis of a hexasaccharide partial sequence of hyaluronan for click chemistry and more

• Marina Bantzi,
• Stephan Rigol and
• Athanassios Giannis

Beilstein J. Org. Chem. 2015, 11, 604–607, doi:10.3762/bjoc.11.67

• oligomers related to HA are highly desired as novel pharmacotherapy targets. Syntheses of HA disaccharides appear for the first time in literature in 1962 from Jeanloz et al. [14] and Takanashi et al. [15]. Since then, many efforts have been done in this field resulting in the synthesis of longer HA

Sequence-specific RNA cleavage by PNA conjugates of the metal-free artificial ribonuclease tris(2-aminobenzimidazole)

• Friederike Danneberg,
• Alice Ghidini,
• Plamena Dogandzhiyski,
• Elisabeth Kalden,
• Roger Strömberg and
• Michael W. Göbel

Beilstein J. Org. Chem. 2015, 11, 493–498, doi:10.3762/bjoc.11.55

• . Here we report a new and mercury-free synthesis of tris(2-aminobenzimidazole) and its conjugation to PNA oligomers. In addition, the results of cleaving experiments with three different RNA substrates are presented. Results and Discussion Alternative reagents to convert thioureas into guanidines

• carboxylic acid 8, which after removal of the solvent was used for conjugation to PNA without further purification (Scheme 3). Conjugation of tris(2-aminobenzimidazole) 8 was performed with fully protected PNA-oligomers still bound to the solid support. To increase the solubility of the final product, 10mers

• yields). Conjugation to PNA oligomers can be readily achieved in high yields, providing an easy way to synthesize sequence specific metal-free artificial nucleases for a wide range of RNA substrates. Due to the tendency of PNA conjugates to form aggregates, a phenomenon not seen with their DNA analogs

Synthesis and chemosensing properties of cinnoline-containing poly(arylene ethynylene)s

• Natalia A. Danilkina,
• Petr S. Vlasov,
• Semen M. Vodianik,
• Andrey A. Kruchinin,
• Yuri G. Vlasov and
• Irina A. Balova

Beilstein J. Org. Chem. 2015, 11, 373–384, doi:10.3762/bjoc.11.43

• dispersity (ĐM = ) of 2.5 for both compounds. In accordance with this data, compounds 10a and 10b should be defined as oligomers. However the common accepted abbreviation for this class of compounds is PAEs (poly(arylene ethynylene)s). This name has also been applied before to compounds with a similar range

• of mass-average molecular weights () [17][19][25]. Therefore in order to avoid using of new unusual terms the oligomers obtained were named PAEs. The structure of oligomers 10a,b was confirmed by 1H and 13C NMR spectroscopy, FTIR spectra and CHN-elemental analysis. In FTIR spectra of compounds 10a,b

• oligomer structures possessing alkylated iodohydroquinone units as the end groups. The presence of iodine in oligomers was also confirmed by the Beilstein test [62]. Regarding the NMR data, the chemical shift values of H and C atoms in both PAEs synthesized do not significantly differ from the chemical

IR and electrochemical synthesis and characterization of thin films of PEDOT grown on platinum single crystal electrodes in [EMMIM]Tf₂N ionic liquid

• Andrea P. Sandoval,
• Marco F. Suárez-Herrera and
• Juan M. Feliu

Beilstein J. Org. Chem. 2015, 11, 348–357, doi:10.3762/bjoc.11.40

• al. [18]. They associated the loop with an autocatalytic mechanism in which the oligomers formed during the first oxidation cycle react as redox mediators with the monomer, but this kind of loops is also characteristic of a nucleation and growth mechanism. The continuous increase of the current

Anionic sigmatropic-electrocyclic-Chugaev cascades: accessing 12-aryl-5-(methylthiocarbonylthio)tetracenes and a related anthra[2,3-b]thiophene

• Laurence Burroughs,
• John Ritchie,
• Mkhethwa Ngwenya,
• Dilfaraz Khan,
• William Lewis and
• Simon Woodward

Beilstein J. Org. Chem. 2015, 11, 273–279, doi:10.3762/bjoc.11.31

• extensive decomposition prevented other characterisation. Based on this model system, it is proposed that intermolecular [2 + 2] reactions of bis-allenes, similar to results in other reported allenic rearrangements to rubrene [27][28], 2c,d result in the formation of numereous stereoisomeric oligomers

Conjugates of methylated cyclodextrin derivatives and hydroxyethyl starch (HES): Synthesis, cytotoxicity and inclusion of anaesthetic actives

• Lisa Markenstein,
• Antje Appelt-Menzel,
• Marco Metzger and
• Gerhard Wenz

Beilstein J. Org. Chem. 2014, 10, 3087–3096, doi:10.3762/bjoc.10.325

• ; occupancy; polymer; sevoflurane; solubility; starch; Introduction Cyclodextrins (CDs), α(1→4) linked cyclic oligomers of anhydroglucose, are produced nowadays in industrial scale [1]. CDs are able to complex hydrophobic or amphiphilic guest molecules in aqueous phase [2]. β-CD, the seven membered ring