Geometric diversity

Ligand-induced Geometrical Diversity Affording New Reactivity of Organoaluminum(m)... 

In 1982, the synthesis and properties of a new polycyclic C2oH2o hydrocarbon, dodecahedrane, was reported [21], The twenty carbon atoms of this molecule are arranged like the vertices of a regular dodecahedron. When, in the early 1960s, H. P. Schultz discussed the topology of the polyhedrane and prismane molecules (vide infra) [22], at that time it was in terms of a geometrical diversion rather than true-life chemistry. Since then it has become real chemistry. 

Boyd, S.M., Beverley, M., Norskov, L. and Hubbard, R.E. Characterising the Geometric Diversity ofFunctional Groups in Chemical Databases. J. Comput.-Aided Mol. Des.,... 

Characterising the Geometric Diversity of Functional Groups in Chemical Databases. 

Martin, R.L., Smit, B., Haranczyk, M. Addressing challenges of identifying geometrically diverse sets of crystalline porous materials. J. Chem. Inf. Model. 52, 308-318 (2012)... 

As it is seen in Table 2, the results for sector blocks are far from satisfactory. This is a problem that may have several causes (e.g. the geometrical diversity of different sector blocks or the quality of the neural network planning software used) which are out of the scope of this paper and are to be dealt with in another research project. To eliminate the problem temporarily, a smaller set of sector blocks was considered, which involved only the West (W) and East (E) sector blocks, each built up of five elementary sectors. For the neural networks of Set B and Set C these were the only sector blocks used by default. 

The vast number of structural isomers and stereoisomers is another property of diamondoids. For instance, octamantane possesses hundreds of isomers in five molecular weight classes. The octamantane class with formula C34H38 and molecular weight 446 has 18 chiral and achiral isomeric structures. Furthermore, there is unique and great geometric diversity with these isomers. For example, rod-shaped diamondoids (the shortest one of which is 1.0 nm), disc-shaped diamondoids, and screw-shaped ones (with different helical pitches and diameters) have been recognized [12]. 

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