Analyse von polymerem Kohlensuboxid durch Röntgenkleinwinkelstreuung

Ballauff, Matthias; Li, Li; Rosenfeldt, Sabine; Dingenouts, N.; Beck, Johannes; Krieger-Beck, Petra

doi:10.1002/ange.200460263

Cited by 3 publications

(2 citation statements)

References 17 publications

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“…A determination of the molar mass and molecular shape of the dissolved polymer in DMF/H 2 O by small-angle X-ray scattering has recently been performed. [21] IR spectroscopy: Infrared spectra were obtained with a Bruker IFS 113 spectrometer at room temperature. The samples were pressed with anhydrous KBr to pellets.…”

Section: Methodsmentioning

confidence: 99%

“…Consequently more recent experimental evidence [12] questions the simple poly-a-pyrone model. In addition it has been shown by small angle X-ray scattering on solutions of poly(carbonsuboxide) [21] that the molar mass has been greatly underestimated in earlier work. [8,12,13] Being an element-selective, inherently quantitative method with excellent local resolution power, solid-state NMR has shown great promise as a structural tool of characterizing disordered solid-state materials.…”

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The Structure of Poly(carbonsuboxide) on the Atomic Scale: A Solid‐State NMR Study

Günne

Beck

Hoffbauer

et al. 2005

Chemistry A European J

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In this contribution we present a study of the structure of amorphous poly(carbonsuboxide) (C3O2)x by 13C solid-state NMR spectroscopy supported by infrared spectroscopy and chemical analysis. Poly(carbonsuboxide) was obtained by polymerization of carbonsuboxide C3O2, which in turn was synthesized from malonic acid bis(trimethylsilylester). Two different 13C labeling schemes were applied to probe inter- and intramonomeric bonds in the polymer by dipolar solid-state NMR methods and also to allow quantitative 13C MAS NMR spectra. Four types of carbon environments can be distinguished in the NMR spectra. Double-quantum and triple-quantum 2D correlation experiments were used to assign the observed peaks using the through-space and through-bond dipolar coupling. In order to obtain distance constraints for the intermonomeric bonds, double-quantum constant-time experiments were performed. In these experiments an additional filter step was applied to suppress contributions from not directly bonded 13C,13C spin pairs. The 13C NMR intensities, chemical shifts, connectivities and distances gave constraints for both the polymerization mechanism and the short-range order of the polymer. The experimental results were complemented by bond lengths predicted by density functional theory methods for several previously suggested models. Based on the presented evidence we can unambiguously exclude models based on gamma-pyronic units and support models based on alpha-pyronic units. The possibility of planar ladder- and bracelet-like alpha-pyronic structures is discussed.

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Section: Methodsmentioning

confidence: 99%

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confidence: 91%

The Structure of Poly(carbonsuboxide) on the Atomic Scale: A Solid‐State NMR Study

Günne

Beck

Hoffbauer

et al. 2005

Chemistry A European J

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Rheinische Friedrich‐Wilhelms‐Universität Bonn

Carr¹

2017

Geschichte Der Anorganischen Chemie

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SummaryEchinoidea (sea urchins) are a group of benthic marine invertebrates that belong to the deuterostome taxon Echinodermata. Although extensive data have been gathered on larval and adult hard-part anatomy of sea urchins, for several reasons the knowledge of echinoid soft tissue anatomy is still fragmentary. For example, published works report differences in various taxa regarding the presence or absence of prominent internal organs such as the primary siphon, the gastric caecum, or the spongy bodies.The major aim of the present study was therefore to evaluate the potential of two non-invasive imaging techniques, namely magnetic resonance imaging (MRI) and micro-computed tomography (µCT), to visualize, in combination with advanced 3D modeling protocols, internal structures of sea urchins and to apply these techniques for large-scale comparative morphological analyses. In order to significantly extend taxon sampling, valuable specimens from museum collections were selected to be included in this study.MRI proved to be ideally suited to depict internal structures of invertebrates non-invasively, especially soft tissues, at isotropic resolutions well below 100 µm. Due to the simple specimen preparation as well as straight-forward imaging protocols, a high specimen throughput could be accomplished. Based on the digital tomographic datasets, 3D models were assembled in order to visualize selected features of echinoid soft tissue anatomy. Although imaging of soft tissues was practically impossible using conventional desktop µCT equipment due to the physical properties inherent in X-ray technology, this technique was successfully employed to visualize sea urchin hard-part anatomy at isotropic resolutions below 20 µm. MRI and µCT can therefore be seen as complementary non-invasive imaging techniques, especially for echinoderm specimens in which soft-and hard-part anatomy are equally present.To explore novel ways of communication and deposition of the acquired datasets as well as 3D models, these were made publicly available through the Internet and by integrating 3D data into PDF-based scientific publications. This approach included also the use of data from a central data repository for protein structures.The axial complex, a highly specialized organ also found in other echinoderm taxa, was then selected for an exemplary comparative study involving dozens of sea urchin species in order to highlight the possibilities offered by non-invasive imaging techniques combined with dissection, histology, and a reappraisal of information from published work. The results suggest an architectural interdependence of the axial complex with various other internal organs present in sea urchins.Finally, an attempt was made to evaluate the potential of echinoid soft tissue structures to extend the current list of morphological characters used for phylogenetic inferences. A set of selected soft tissue characters was therefore assembled and evaluated for every major sea urchin taxon. The results provide significant phylogenetic informa...

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Self-Organization of Coil−Ring−Coil Structures into Tubular Supramolecular Polymer Brushes: Synthesis, Morphology, and Growth

et al. 2010

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Shape-persistent macrocycles based on the phenylene−ethynylene−butadiynylene backbone with extraannular amino groups were synthesized by the oxidative dimerization of the corresponding (BOC-protected) half-ring bisacetylenes. ABA block structures with a central rigid macrocycle and a flexible periphery (oligoalkyl and oligostyryl groups) were subsequently obtained by carbodiimide directed coupling of the macrocyclic diamines with the corresponding carboxylic acids. Depending on the solvent, an aggregation of the compounds toward tubular supramolecular polymer brushes could be induced. Cryogenic transmission electron microscopy and small-angle neutron scattering reveal the tubelike aggregates in solution. Atomic force microscopy confirms the morphology of these aggregates after casting onto surfaces. The aggregate growth occurs remarkably slowly. Solvophobic interactionsgood solubility of the flexible substituents and weak solubility of the rigid macrocyclecombined with the oblate shape of the latter are determined as driving forces for the directed self-organization.

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Analyse von polymerem Kohlensuboxid durch Röntgenkleinwinkelstreuung

Cited by 3 publications

References 17 publications

The Structure of Poly(carbonsuboxide) on the Atomic Scale: A Solid‐State NMR Study

The Structure of Poly(carbonsuboxide) on the Atomic Scale: A Solid‐State NMR Study

Rheinische Friedrich‐Wilhelms‐Universität Bonn

Self-Organization of Coil−Ring−Coil Structures into Tubular Supramolecular Polymer Brushes: Synthesis, Morphology, and Growth

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