controlling-size-shape-stability-supramolecular-polymers

Controlling the Size, Shape and Stability of Supramolecular Polymers in Water

For aqueous based supramolecular polymers, the simultaneous control over shape, size and stability is very difficult1. At the same time, the ability to do ...

Westfälische Wilhelms-Universität Münster

Enzymes are a source of inspiration for chemists attempting to create versatile synthetic catalysts. In order to arrive at a polymeric chain carrying catalytic units separated spatially, it is a prerequisite to fold these polymers in water into well-defined compartmentalized architectures thus creating a catalytic core. Herein, we report the synthesis, physical properties, and catalytic activity of a water-soluble segmented terpolymer in which a helical structure in the apolar core is created around a ruthenium-based catalyst. The supramolecular chirality of this catalytic system is the result of the self-assembly of benzene-1,3,5-tricarboxamide side chains, while the catalyst arises from the sequential ruthenium-catalyzed living radical polymerization of the different monomers followed by ligand exchange. The polymers exhibit a two-state folding process and show transfer hydrogenation in water.

Single-chain folding of polymers for catalytic systems in water.

The supramolecular oligomerization of three water-soluble C(3)-symmetrical discotic molecules is reported. The compounds all possess benzene-1,3,5-tricarboxamide cores and peripheral Gd(III)-DTPA (diethylene triamine pentaacetic acid) moieties, but differ in their linker units and thus in their propensity to undergo secondary interactions in H(2)O. The self-assembly behavior of these molecules was studied in solution using circular dichroism, UV/Vis spectroscopy, nuclear magnetic resonance, and cryogenic transmission electron microscopy. The aggregation concentration of these molecules depends on the number of secondary interactions and on the solvophobic character of the polymerizing moieties. Hydrophobic shielding of the hydrogen-bonding motif in the core of the discotic is of paramount importance for yielding stable, helical aggregates that are designed to be restricted in size through anti-cooperative, electrostatic, repulsive interactions.

Controlled supramolecular oligomerization of C3-symmetrical molecules in water: the impact of hydrophobic shielding.

A convenient method to prepare supramolecular bioconjugates in a facile and scalable manner is by a modular approach, whereby self-assembling units and peptides are coupled using oxime chemistry. We here report syntheses of bioactive ureidopyrimidinone-based peptide conjugates, and their resultant self-assembly into fibrous structures.

Modular synthesis of supramolecular ureidopyrimidinone-peptide conjugates using an oxime ligation strategy.

Nanometer-sized materials offer a wide range of applications in biomedical technologies, particularly imaging and diagnostics. Current scaffolds in the nanometer range predominantly make use of inorganic particles, organic polymers or natural peptide-based macromolecules. In contrast we hereby report a supramolecular approach for the preparation of self-assembled dendritic-like nanoparticles for applications as MRI contrast agents. This strategy combines the benefits from low molecular weight imaging agents with the ones of high molecular weight. Their in vitro properties are confirmed by in vivo measurements: post injection of well-defined and meta-stable nanoparticles allows for high-resolution blood-pool imaging, even at very low Gd(III) doses. These dynamic and modular imaging agents are an important addition to the young field of supramolecular medicine using well-defined nanometer-sized assemblies.

Article	Year
Journal of the American Chemical Society\| PubMed ID: 18646752	2008
Chemical communications (Cambridge, England)\| PubMed ID: 18688318	2008
Chemistry (Weinheim an der Bergstrasse, Germany)\| PubMed ID: 18752246	2008
Organic & biomolecular chemistry\| PubMed ID: 20448900	2010
Proceedings of the National Academy of Sciences of the United States of America\| PubMed ID: 20921365	2010
Single-chain folding of polymers for catalytic systems in water. Journal of the American Chemical Society\| PubMed ID: 21405022	2011
Controlled supramolecular oligomerization of C3-symmetrical molecules in water: the impact of hydrophobic shielding. Chemistry (Weinheim an der Bergstrasse, Germany)\| PubMed ID: 21432920	2011
Journal of the American Chemical Society\| PubMed ID: 21797209	2011
Modular synthesis of supramolecular ureidopyrimidinone-peptide conjugates using an oxime ligation strategy. Chemical communications (Cambridge, England)\| PubMed ID: 22010132	2012
Paramagnetic self-assembled nanoparticles as supramolecular MRI contrast agents. Contrast media & molecular imaging\| PubMed ID: 22539406	2012

Pol Besenius

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