Publications by authors named "Marcel Koenigs"

6 Publications

  • Page 1 of 1

Supramolecular Macrostructures of UPy-Functionalized Carbon Nanotubes.

Chemistry 2015 Sep 13;21(40):14179-85. Epub 2015 Aug 13.

Center of Excellence for Nanostructured Materials (CENMAT), INSTM UdR di Trieste, Dipartimento di Scienze Chimiche e Farmaceutiche, University of Trieste, Piazzale Europa 1, TS I-34127 (Italy).

Carbon nanotubes (CNTs) are considered excellent materials for the construction of flexible displays due to their nanoscale dimensions and unique physical and chemical properties. By using the recognition properties of 2-ureido-4[1H]pyrimidinone (UPy), a versatile and simple methodology was demonstrated for the construction of macroscopic structures based on UPy-CNT/polymer composites prepared by a combination of two functionalization approaches: 1) covalent attachment of UPy pendants on the multiwalled CNT surface (UPy-MWCNTs) and 2) directed self-assembly of UPy-MWCNTs within polymers bearing UPy pendants (Bis-UPy 1 and Bis-UPy 2) by quadruple complementary DDAA-AADD hydrogen-bond recognition (D=donor, A=acceptor).
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http://dx.doi.org/10.1002/chem.201502022DOI Listing
September 2015

Triggering activity of catalytic rod-like supramolecular polymers.

Chemistry 2015 Feb 22;21(9):3682-90. Epub 2015 Jan 22.

Institute for Complex Molecular Systems, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven (The Netherlands).

Supramolecular polymers based on benzene-1,3,5-tricarboxamides (BTAs) functionalized with an L- or D-proline moiety display high catalytic activity towards aldol reactions in water. High turnover frequencies (TOF) of up to 27×10(-4) s(-1) and excellent stereoselectivities (up to 96% de, up to 99% ee) were observed. In addition, the catalyst could be reused and remained active at catalyst loadings and substrate concentrations as low as 0.1 mol % and 50 mM, respectively. A temperature-induced conformational change in the supramolecular polymer triggers the high activity of the catalyst. The supramolecular polymer's helical sense in combination with the configuration of the proline (L- or D-) is responsible for the observed selectivity.
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http://dx.doi.org/10.1002/chem.201405410DOI Listing
February 2015

Topochemical polymerization in self-assembled rodlike micelles of bisurea bolaamphiphiles.

Soft Matter 2014 Feb;10(7):952-6

Rod-like micelles, formed from bolaamphiphiles with oligo(ethylene oxide) hydrophilic outer segments and a hydrophobic segment with diacetylene flanked by two urea moieties, were covalently fixated by topochemical photopolymerization to high degrees of polymerization by optimizing the hydrophobic core and the hydrophilic periphery of the bolaamphiphiles. Analysis of the polymerized product with dynamic light scattering in chloroform showed degrees of polymerization of approximately 250. Cryo-TEMof bolaamphiphiles before and after UV irradiation showed that the morphology of the rods was conserved upon topochemical polymerization.
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http://dx.doi.org/10.1039/c3sm52605dDOI Listing
February 2014

Triple helix formation in amphiphilic discotics: demystifying solvent effects in supramolecular self-assembly.

J Am Chem Soc 2014 Jan 19;136(1):336-43. Epub 2013 Dec 19.

Institute of Complex Molecular Systems, Laboratory of Macromolecular and Organic Chemistry, Eindhoven University of Technology , P.O. Box 513, 5600 MB, Eindhoven, The Netherlands.

A set of chiral, amphiphilic, self-assembling discotic molecules based on the 3,3'-bis(acylamino)-2,2'-bipyridine-substituted benzene-1,3,5-tricarboxamide motif (BiPy-BTA) was prepared. Amphiphilicity was induced into the discotic molecules by an asymmetrical distribution of alkyl and oligo(ethylene oxide) groups in the periphery of the molecules. Small-angle X-ray scattering, cryogenic transmission electron microscopy, and circular dichroism spectroscopy measurements were performed on the discotic amphiphiles in mixtures of water and alcohol at temperatures between 0 °C an 90 °C. The combined results show that these amphiphilic discotic molecules self-assemble into supramolecular fibers consisting of either one or three discotic molecules in the fiber cross-section and that the presence of water induces the bundling of the supramolecular fibers. The rich phase behavior observed for these molecules proves to be intimately connected to the mixing thermodynamics of the water-alcohol mixtures.
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http://dx.doi.org/10.1021/ja4104183DOI Listing
January 2014

Supramolecular polymerization in water harnessing both hydrophobic effects and hydrogen bond formation.

Chem Commun (Camb) 2013 Mar 31;49(19):1963-5. Epub 2013 Jan 31.

Institute for Complex Molecular Systems, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands.

The formation of supramolecular polymers in water through rational design of a benzene-1,3,5-tricarboxamide (BTA) motif is presented. Intermolecular hydrogen bonding and hydrophobic effects cooperate in the self-assembly into long fibrillar aggregates. Minimal changes in molecular structure significantly affect the internal packing of the aggregates.
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http://dx.doi.org/10.1039/c3cc38949aDOI Listing
March 2013

Injectable hydrogels from segmented PEG-bisurea copolymers.

Biomacromolecules 2012 Dec 28;13(12):3966-76. Epub 2012 Nov 28.

Laboratory for Macromolecular and Organic Chemistry, Department of Mechanical Engineering, Institute for Complex Molecular Systems, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands.

We describe the preparation of an injectable, biocompatible, and elastic segmented copolymer hydrogel for biomedical applications, with segmented hydrophobic bisurea hard segments and hydrophilic PEG segments. The segmented copolymers were obtained by the step growth polymerization of amino-terminated PEG and aliphatic diisocyanate. Due to their capacity for multiple hydrogen bonding within the hydrophobic segments, these copolymers can form highly stable gels in water at low concentrations. Moreover, the gels show shear thinning by a factor of 40 at large strain, which allows injection through narrow gauge needles. Hydrogel moduli are highly tunable via the physical cross-link density and the length of the hydrophilic segments. In particular, the mechanical properties can be optimized to match the properties of biological host tissues such as muscle tissue and the extracellular matrix.
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http://dx.doi.org/10.1021/bm301242vDOI Listing
December 2012
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