Hierarchically organized substructure

Computer generation, storage and retrieval of substructures is greatly facilitated, when the mathematical model of structural chemistry is employed to generate a hierarchically organized substructure file in a systematic fashion. Such hierarchical ordering is not only a prerequisite in avoiding duplication of... 

However, one of the most successfiil approaches to systematically encoding substructures for NMR spectrum prediction was introduced quite some time ago by Bremser [9]. He used the so-called HOSE (Hierarchical Organization of Spherical Environments) code to describe structures. As mentioned above, the chemical shift value of a carbon atom is basically influenced by the chemical environment of the atom. The HOSE code describes the environment of an atom in several virtual spheres - see Figure 10.2-1. It uses spherical layers (or levels) around the atom to define the chemical environment. The first layer is defined by all the atoms that are one bond away from the central atom, the second layer includes the atoms within the two-bond distance, and so on. This idea can be described as an atom center fragment (ACF) concept, which has been addressed by several other authors in different approaches [19-21]. 

We have started the design of a model program to extract irreducible R-matrices from known reactions, to put them into canonical order, and to set the sequence of references in a hierarchical file, that is organized in a similar way as substructure files described in (5.1.3). 

Figure 5 Schematic illustration of the structure formation processes in (a) polypeptides and (b) amphiphilic AB block copolymers. While the block copolymer forms micellar aggregates with a simple core-shell fine structure, the peptide organization leads to distinct nanostructures with a precise hierarchical inner structure ( primary structure the amino acid sequence of the peptide chains secondary structure locally defined substructures In a single protein molecule tertiary structure spatial arrangement of the secondary structures in a 3D structure of a single protein molecule and quaternary structure arrangement of tertiary structure subunit assembly). Reprinted with permission from Borner, H. G. Prog. Polym. Sci. 2009,34, 811-851. Copyright 2009, Elsevier.

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