Supramolecular Characteristics

Schaumann, G. E. (2006a). Review articles. Soil organic matter beyond molecular structure. Part I Macromolecular and supramolecular characteristics. J. Plant Nutr. Soil Sci. 169. 145-156. 

Discussing the effect of the peroxide content, the structural parameters (MW, MWD) and the supramolecular characteristics such as the spherulite size and distribution on the fracture toughness parameters and the failure mechanisms. The analysis is carried out on real injected CRPPs in which neither thermal treatment was applied nor nucleating agents were used. 

A set of controlled-rheology propylene homopelymers and ethylene-propylene block copelymers have been analyzed. The investigation has been focussed on the influence of the DTBP addition on the supramolecular characteristics as the spherulite size and distributuion... 

These attempts to make the theory fit experimental results are unnatural. They eouldn t overeome limitations of the initial lattiee model whieh doesn t take into eonsideration structural, first of all supramolecular characteristics of polymers. Flori has removed many elassieal theory version defects [143] from his modified thermodynamieal theory of liquid blends, where he used the main aspects of the corresponding states model, whieh Prigozhin [144] had worked out for solutions. We will not go into details of this theory, whieh has been discussed, eommented and further developed by many well-known seientists (see for example [129,131,132-135,145-149]). Let us just mention that the Flori theory has natiually taken into account some speeifie structural features of the real polymer solutions, sueh as ehange of component volumes during mixing, association of components and ete. 

Ribosomes, the supramolecular assemblies where protein synthesis occurs, are about 65% RNA of the ribosomal RNA type. Ribosomal RNA (rRNA) molecules fold into characteristic secondary structures as a consequence of intramolecular hydrogen bond interactions (marginal figure). The different species of rRNA are generally referred to according to their sedimentation coefficients (see the Appendix to Chapter 5), which are a rough measure of their relative size (Table 11.2 and Figure 11.25). 

There is significant interest in zinc sulfide, selenide, and oxide materials and while extensive discussion is not appropriate here, a number of novel complexes that have been developed for their deposition characteristics of these important semiconductors will be highlighted in the context of the ligand types. Zinc has also been used in supramolecular building blocks as a structural element, much as in zinc finger proteins. In these cases the lack of redox chemistry is... 

From the atomic to the macroscopic level chirality is a characteristic feature of biological systems and plays an important role in the interplay of structure and function. Originating from small chiral precursors complex macromolecules such as proteins or DNA have developed during evolution. On a supramolecular level chirality is expressed in molecular organization, e.g. in the secondary and tertiary structure of proteins, in membranes, cells or tissues. On a macroscopic level, it appears in the chirality of our hands or in the asymmetric arrangement of our organs, or in the helicity of snail shells. Nature usually displays a preference for one sense of chirality over the other. This leads to specific interactions called chiral recognition. 

Perhaps the common characteristic of all contributions to this volume is the permanent concern about the intimate relationships between the structural and electronic properties. Indeed, the careful design of increasingly complex molecular and supramolecular architectures allows us now to anticipate many molecular and solid state properties, but the final solid state structures are always the results of many competing interactions. The resulting electronic properties of these radical assemblies, whether conductivity or magnetism, are always very sensitive to minute modifications of their solid state structures and one of the main difficulties through... 

Second coordination shell complexation of hydrophilic ferrioxamine B produces a hydrophobic supramolecular siderophore-ionophore assembly. The hydrophobic characteristic in concert... 

At shorter distances, particularly those characteristic of H-bonded and other charge-transfer complexes, the concepts of partial covalency, resonance, and chemical forces must be extended to intramolecular species. In such cases the distinction between, e.g., the covalent bond and the H-bond may become completely arbitrary. The concept of supramolecular clusters as fundamental chemical units presents challenges both to theory and to standard methods of structural characterization. Fortunately, the quantal theory of donor-acceptor interactions follows parallel lines for intramolecular and intermolecular cases, allowing seamless description of molecular and supramolecular bonding in a unified conceptual framework. In this sense, supramolecular aggregation under ambient thermal conditions should be considered a true chemical phenomenon. 

It has been shown frequently that without the presence of strong intermolecular interactions, discotic molecules are highly mobile in the liquid crystalline state.1 They undergo both lateral as well as rotational translations, resulting in the absence of positional order. Similarly, such discotics also freely rotate in the columnar aggregates they form in solution. This lack of positional order in the columns accounts for the absence of chiral or helical supramolecular order. We will demonstrate this characteristic using results obtained for triphenylenes. 

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