ChemInform Abstract: Building Blocks of Oligosaccharides. Part 74. Synthesis of a Hexapeptide with Two Disaccharide Side-Chains Representing the Sequence 43 to 48 of Asialoglycophorin A.

We investigated the adsorption properties of the newly synthesized, hydrophobically functionalized polyelectrolyte (HF-PE), poly(4-styrenesulfonic-co-maleic acid) copolymer (PSS/MA). The hydrophobic alkyl side chains (C12 or C16) were incorporated into the polyelectrolyte backbone via the labile amid linker to obtain the soft HF-PE product with the assumed amount of 15% and 40% degree of grafting for every length of the alkyl chain, i.e., PSS/MA-g-C12NH2 (15% or 40%) as well as PSS/MA-g-C16NH2 (15% or 40%). In the present contribution, we determined both the effect of grafting density and the length of alkyl chain on adsorption at water/air and water/decane interfaces, as well as on top of the polyelectrolyte multilayer (PEM) deposited on a solid surface. The dependence of the interfacial tension on copolymer concentration was investigated by the pendant drop method, while the adsorption at solid surface coated by poly(diallyldimethylammonium chloride)/poly(styrene sulphonate) PEM by the quartz crystal microbalance with dissipation (QCM-D), attenuated total reflection Fourier transform infrared spectroscopy (FTIR-ATR) and contact angle analysis. We found that surface activity of the hydrophobized copolymer was practically independent of the grafting ratio for C16 side chains, whereas, for C12, the copolymer with a lower grafting ratio seemed to be more surface active. The results of QCM-D and FTIR-ATR experiments confirmed the adsorption of hydrophobized copolymer at PEM along with the modification of water structure at the interface. Finally, it can be concluded that the hydrophobically modified PSS/MA can be successfully applied either as the efficacious emulsifier for the formation of (nano)emulsions for further active substances encapsulation using the sequential adsorption method or as one of the convenient building blocks for the surface modification materials.

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Polar tagging in the synthesis of monodisperse oligo(p-phenyleneethynylene)s and an update on the synthesis of oligoPPEs

Beilstein Journal of Organic Chemistry ◽

10.3762/bjoc.6.57 ◽

2010 ◽

Vol 6 ◽

Cited By ~ 11

Author(s):

Dhananjaya Sahoo ◽

Susanne Thiele ◽

Miriam Schulte ◽

Navid Ramezanian ◽

Adelheid Godt

Keyword(s):

Chromatographic Separation ◽

Side Reaction ◽

Building Blocks ◽

Protecting Groups ◽

Side Chains ◽

Protecting Group ◽

Synthetic Route ◽

End Groups ◽

Pure Compounds ◽

Better Than

One important access to monodisperse (functionalized) oligoPPEs is based on the orthogonality of the alkyne protecting groups triisopropylsilyl and hydroxymethyl (HOM) and on the polar tagging with the hydroxymethyl moiety for an easy chromatographic separation of the products. This paper provides an update of this synthetic route. For the deprotection of HOM protected alkynes, γ-MnO2 proved to be better than (highly) activated MnO2. The use of HOM as an alkyne protecting group is accompanied by carbometalation as a side reaction in the alkynyl–aryl coupling. The extent of carbometalation can be distinctly reduced through substitution of HOM for 1-hydroxyethyl. The strategy of polar tagging is extended by embedding ether linkages within the solubilising side chains. With building blocks such as 1,4-diiodo-2,5-bis(6-methoxyhexyl) less steps are needed to assemble oligoPPEs with functional end groups and the isolation of pure compounds becomes simple. For the preparation of 1,4-dialkyl-2,5-diiodobenzene a better procedure is presented together with the finding that 1,4-dialkyl-2,3-diiodobenzene, a constitutional isomer of 1,4-dialkyl-2,5-diiodobenzene, is one of the byproducts.

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Assembling nanotubes with cyclic peptoids

Acta Crystallographica Section A Foundations and Advances ◽

10.1107/s2053273314094364 ◽

2014 ◽

Vol 70 (a1) ◽

pp. C563-C563

Author(s):

Consiglia Tedesco ◽

Irene Izzo ◽

Francesco De Riccardis ◽

Gavin Vaughan ◽

Michela Brunelli ◽

...

Keyword(s):

Solid State ◽

Hydrogen Bonds ◽

Biological Activities ◽

Variable Temperature ◽

Chemical Properties ◽

Functional Materials ◽

Building Blocks ◽

Amide Proton ◽

Side Chains ◽

Peptide Backbone

Cyclic alpha-peptoids hold the attention of both synthetic and supramolecular chemists for their biostability and potential diversity but also for their elegant and intriguing architectures.[1] Peptoids differ from peptides in the side chains, which are shifted by one position along the peptide backbone to the nitrogen atom to give N-substituted oligoglycine. The lack of the amide proton prevents the formation of NH···OC hydrogen bonds and weaker interactions, as CH···OC hydrogen bonds and CH-pi interactions, play a key role. Inter-annular CH···OC hydrogen bonds can provide face to face or side by side arrangement of macrocycles mimicking beta-sheet secondary structure in proteins.[2] In particular, the role of side chains in the solid state assembly of peptoid macrocycles will be discussed to show how they can promote the formation of a peptoid nanotube by acting as pillars, extending vertically with respect to the macrocycle planes. [3] Examples of the solid state assembly of free and metallated cyclic peptoids will be reported to show their extreme versatility as building blocks for designing new materials, with novel chemical properties and defined biological activities. In particular the first crystal structure of a recently synthesized novel cyclic alpha-peptoid, containing open channels with a radius of approximately 7 Å, will be discussed as a case of the successful engineering of cyclopeptoid crystals. In figure it is shown the channel void surface as seen along the a axis (0.0003 au, CrystalExplorer 3.1). The results of recent variable temperature high resolution XRPD measurements performed at ESRF beamline ID31 will be also reported to highlight the unusual thermal stability of this class of compounds and how the mobility of the side chains may be exploited to prepare new functional materials. EU FP7-People- IRSES grant number 319011 is gratefully acknowledged.

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Synthesis of new pyrazolo[1,2,3]triazines by cyclative cleavage of pyrazolyltriazenes

Beilstein Journal of Organic Chemistry ◽

10.3762/bjoc.17.187 ◽

2021 ◽

Vol 17 ◽

pp. 2773-2780

Author(s):

Nicolai Wippert ◽

Martin Nieger ◽

Claudine Herlan ◽

Nicole Jung ◽

Stefan Bräse

Keyword(s):

Building Blocks ◽

Side Chains ◽

Protective Group ◽

Cleavage Reaction

We describe the synthesis of so far synthetically not accessible 3,6-substituted-4,6-dihydro-3H-pyrazolo[3,4-d][1,2,3]triazines as nitrogen-rich heterocycles. The target compounds were obtained in five steps, including an amidation and a cyclative cleavage reaction as key reaction steps. The introduction of two side chains allowed a variation of the pyrazolo[3,4-d][1,2,3]triazine core with commercially available building blocks, enabling the extension of the protocol to gain other derivatives straightforwardly. Attempts to synthesize 3,7-substituted-4,7-dihydro-3H-pyrazolo[3,4-d][1,2,3]triazines, the regioisomers of the successfully gained 3,6-substituted 4,6-dihydro-3H-pyrazolo[3,4-d][1,2,3]triazines, were not successful under similar conditions due to the higher stability of the triazene functionality in the regioisomeric precursors and thus, the failure of the removal of the protective group.

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