Highlight Publications 2017

Edge Functionalization of Structurally Defined Graphene Nanoribbons for Modulating the Self- Assembled Structures
Ashok Keerthi, Boya Radha, Daniele Rizzo, Hao Lu, Valentin Diez Cabanes, Ian Cheng-Yi Hou, David Beljonne, Jérôme Cornil, Cinzia Casiraghi, Martin Baumgarten, Klaus Müllen, Akimitsu Narita
Edge Functionalization of Structurally Defined Graphene Nanoribbons for Modulating the Self- Assembled Structures
Edge functionalization of bottom-up synthesized graphene nanoribbons (GNRs) with anthraquinone (AQ) and naphthalene/perylene monoimide (NMI/PMI) units has been achieved through a Suzuki coupling of polyphenylene precursors bearing bromo groups, prior to the intramolecular oxidative cyclodehydrogenation. High efficiency of the substitution has been validated by MALDI-TOF MS analysis of the functionalized precursors and FT-IR, Raman and XPS analyses of the resulting GNRs. Moreover, AFM measurements demonstrated the modulation of the self-assembling behavior of the edge-functionalized GNRs, revealing that GNR-PMI formed an intriguing rectangular network. This result suggests the possibility of programming the supramolecular architecture of GNRs by tuning the functional units.
© ACS (2017)
Structure and unique self-assembled structure of GNR-PMI visualized by atomic force microscope.
Exploration of pyrazine-embedded antiaromatic polycyclic hydrocarbons generated by solution and on-surface azomethine ylide homocoupling
Xiao-Ye Wang, Marcus Richter, Yuanqin He, Jonas Björk, Alexander Riss, Raju Rajesh, Manuela Garnica, Felix Hennersdorf, Jan J. Weigand, Akimitsu Narita, Reinhard Berger, Xinliang Feng, Willi Auwärter, Johannes V. Barth, Carlos-Andres Palma, Klaus Müllen
Exploration of pyrazine-embedded antiaromatic polycyclic hydrocarbons generated by solution and on-surface azomethine ylide homocoupling
Nanographenes, namely polycyclic aromatic hydrocarbons (PAHs) with nanoscale dimensions (>1 nm), are atomically precise cutouts from graphene. They represent prime models to enhance the scope of chemical and physical properties of graphene through structural modulation and functionalization. Defined nitrogen doping in nanographenes is particularly attractive due to its potential for increasing the number of π-electrons, with the possibility of introducing localized antiaromatic ring elements. Herein we present azomethine ylide homocoupling as a strategy to afford internally nitrogen-doped, non-planar PAH in solution and planar nanographene on surfaces, with central pyrazine rings. Localized antiaromaticity of the central ring is indicated by optical absorption spectroscopy in conjunction with theoretical calculations. Our strategy opens up methods for chemically tailoring graphene and nanographenes, modified by antiaromatic dopants.
© Nature Publishing Group (2017)
Exploration of pyrazine-embedded antiaromatic polycyclic hydrocarbons
Controlling the polymer microstructure in anionic polymerization by compartmentalization
Elisabeth Rieger, Jan Blankenburg, Eduard Grune, Manfred Wagner, Katharina Landfester, and Frederik R. Wurm
Controlling the polymer microstructure in anionic polymerization by compartmentalization
Compartmentalization is the spatial separation of reagents inside of organisms, which allows nature to prepare complex molecules. In contrast, polymer chemistry normally uses sequential monomer addition to prepare macromolecular architectures. In the synthesis lab an emulsion is the easiest way of confining a reaction: we use an emulsion template to force an ideal (random) copolymerization of two comonomers into gradient copolymers in a one-pot and one-shot reaction, without the need for sequential monomer addition. Physical separation of the two monomers is achieved by selective solubility in the dispersed and the continuous phase to control the incorporation probability of both monomers. In addition, confinement of the propagation to the nano-droplets allows further tuning of the gradient by different levels of dilution of the continuous phase.
© Wiley VCH (2017)
Schematic representation of homogeneous copolymerization to random, and emulsion copolymerization to gradient copolymers from the same monomer pair.
Fabrication of defined polydopamine nanostructures by DNA origami-templated polymerization
Yu Tokura, Sean Harvey, Chaojian Chen, Yuzhou Wu, David Y.W. Ng, Tanja Weil
Fabrication of defined polydopamine nanostructures by DNA origami-templated polymerization
A versatile, bottom-up approach allows the controlled fabrication of polydopamine (PD) nanostructures on DNA origami. PD is a biosynthetic polymer that has been investigated as an adhesive and promising surface coating material. DNA origami decorated with multiple horseradish peroxidase-mimicking DNAzyme motifs was used to control the shape and size of PD formation with nanometer resolution. These fabricated PD nanostructures can serve as “supramolecular glue” for controlling DNA origami conformations. Facile liberation of the PD nanostructures from the DNA origami templates has been achieved in acidic medium. This presented DNA origami-controlled polymerization of a highly crosslinked polymer provides a unique access towards anisotropic PD architectures with distinct shapes that were retained even in the absence of the DNA origami template.
© Wiley VCH (2017)
Nanofabrication of Precise Polydopamine Architectures
Directing Intracellular Supramolecular Assembly with N-heteroaromatic Quaterthiophene Analogues
David Y.W. Ng, Roman Vill, Yuzhou Wu, Kaloian Koynov, Yu Tokura, Weina Liu, Susanne Sihler, Andreas Kreyes, Sandra Ritz, Holger Barth, Ulrich Ziener, Tanja Weil
Directing Intracellular Supramolecular Assembly with N-heteroaromatic Quaterthiophene Analogues
Self-assembly in situ, where synthetic molecules are programmed to organize in a complex environment can be a unique strategy to influence cellular functions. Here we present oligothiophene analogues that target, locate and dynamically self-report their supramolecular behavior within the confinement of a cell. Through the recognition of their chemical structure, we show that the cell provides different pathways for self-assembly that are traced with fluorescence microscopy. Their molecular organization emits in distinct fluorescent bands and the control each form is achieved by time, temperature as well as the use of the intracellular transport inhibitor, bafilomycin A1. We show the importance of both intrinsic and extrinsic factors for self-organization and the potential of such a platform toward developing synthetic functional components within living cells.
© David Ng / MPI-P (2017)
Overview of cellular pathways and its influence on self-organization of the oligothiophene analogues
Biological fabrication of cellulose fibers with tailored properties
Filipe Natalio, Regina Fuchs, Sidney R. Cohen, Gregory Leitus, Gerhard Fritz-Popovski, Oskar Paris, Michael Kappl, Hans-Jürgen Butt
Biological fabrication of cellulose fibers with tailored properties
Filipe Natalio from the Weizmann Institute of Science Israel, together with colleagues from the MPI-P and from Leoben, Austria, developed a method for biofabrication of functional cotton. Cotton ovules, were incubated in media containing glucose molecules (the molecular building blocks of cellulose fibers) that were specifically modified. Dye molecules or molecular magnets linked to glucose were taken up by the ovules and metabolized into cellulose fibers that became colored or exhibiting magnetic response. This new concept of material farming opens perspectives for plant based biofabrication of functional materials without genetic modifications.
© Filipe Natalio (2017)
Optical microscopy image of cotton fibers containing a fluorescent dye. Dye molecules were integrated into fibers via the metabolic pathways of cotton ovules, incubating them with specifically designed glucose molecules containing the dye.
 
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