Elucidating dynamic behavior of synthetic supramolecular polymers in water by hydrogen/deuterium exchange mass spectrometry

A comprehensive understanding of the structure, self-assembly mechanism, and dynamics of one-dimensional supramolecular polymers in water is essential for their application as biomaterials. Although a plethora of techniques are available to study the first two properties, there is a paucity in possibilities to study dynamic exchange of monomers between supramolecular polymers in solution. We recently introduced hydrogen/deuterium exchange mass spectrometry (HDX-MS) to characterize the dynamic nature of synthetic supramolecular polymers with only a minimal perturbation of the chemical structure. To further expand the application of this powerful technique some essential experimental aspects have been reaffirmed and the technique has been applied to a diverse library of assemblies. HDX-MS is widely applicable if there are exchangeable hydrogen atoms protected from direct contact with the solvent and if the monomer concentration is sufficiently high to ensure the presence of supramolecular polymers during dilution. In addition, we demonstrate that the kinetic behavior as probed by HDX-MS is influenced by the internal order within the supramolecular polymers and by the self-assembly mechanism.MINECO, Spain, Grant/Award Number: IJCI-2015-252389; Marie Curie FP7 SASSYPOL ITN program, Grant/Award Number: 607602; European Research Council, Grant/Award Number: 788618; Dutch Ministry of Education, Culture and Science, Grant/Award Number: 024.001.03

Chemiluminescence in action. Syntheses, properties, and applications of 1,2-dioxetanes

This dissertation describes a multidisciplinary study of the synthesis, properties, and applications of 1,2-dioxetanes. 1,2-Dioxetanes are energy-rich cyclic peroxides, which cleave, when heated, into two carbonyl compounds. One of the carbonyl compounds is formed in the excited state. The transition of the excited-state carbonyl to its ground state gives rise to the emission of light. Luminescence which originates from a chemical reaction is called chemiluminescence. Since the discovery of 1,2-dioxetanes, investigations in this field have concentrated on the synthesis, properties, and fundamental aspects of the chemiluminescence of these species. Thus far, no applications of these chemical sources of light are known. Our interest in this area was caused by the possibility of exploring 1,2-dioxetanes and their chemiluminescence as an analytical tool, a probe for dynamic processes, or as light source with characteristic properties. ... Zie: Epilogue

Oligodimethylsiloxane-Oligoproline Block Co-Oligomers: the Interplay between Aggregation and Phase Segregation in Bulk and Solution

Discrete block co-oligomers (BCOs) assemble into highly ordered nanostructures, which adopt a variety of morphologies depending on their environment. Here, we present a series of discrete oligodimethylsiloxane-oligoproline (oDMS-oPro) BCOs with varying oligomer lengths and proline end-groups, and study the nanostructures formed in both bulk and solution. The conjugation of oligoprolines to apolar siloxanes permits a study of the aggregation behavior of oligoproline moieties in a variety of solvents, including a highly apolar solvent like methylcyclohexane. The apolar solvent is more reminiscent of the polarity of the siloxane bulk, which gives insights into the supramolecular interactions that govern both bulk and solution assembly processes of the oligoproline. This extensive structural characterization allows the bridging of the gap between solution and bulk assembly. The interplay between the aggregation of the oligoproline block and the phase segregation induced by the siloxane drives the assembly. This gives rise to disordered, micellar microstructures in apolar solution and crystallization-driven lamellar nanostructures in the bulk. While most di- and triblock co-oligomers adopt predictable morphological features, one of them, oDMS15-oPro6-NH2, exhibits pathway complexity leading to gel formation. The pathway selection in the complex interplay between aggregation and phase segregation gives rise to interesting material properties.ISSN:0002-7863ISSN:1520-512

Supramolecular Double Helices from Small C3-symmetrical Molecules Aggregated in Water

Supramolecular fibers in water, micrometers long and several nanometers in width, are amongst the most studied nanostructures for biomedical applications. These supramolecular polymers are formed through a spontaneous self-assembly process of small amphiphilic molecules by specific secondary interactions. Although many compounds do not possess a stereocenter, recent studies suggest the (co-)existence of helical structures, albeit in racemic form. Here, we disclose a series of supramolecular (co)polymers based on water-soluble benzene-1,3,5-tricarboxamides (BTAs) that form double helices, fibers that for long were thought to be chains of single molecules stacked in one dimension (1D). Detailed cryo-TEM studies and subsequent 3D-volume reconstructions unveiled helical repeats, ranging from 15-30 nanometer. Most remarkable, the pitch can be tuned through the composition of the copolymers, where two different monomers with the same core but different peripheries are mixed in various ratios. Like in lipid bilayers, the hydrophobic shielding in the aggregates of these disc-shaped molecules is proposed to be best obtained by dimer-formation promoting supramolecular double helices. It is anticipated that many of the supramolecular polymers in water will have a thermodynamic stable structure being such a double helix, although small structural changes can yield single stacks as well. Hence, it is essential to perform detailed analyses prior to sketching a molecular picture of these 1D fibers