engleski

Cluster analysis as a tool for molecular fragmentation in the search of low-energy conformations by the overlapping spheres method

The overlapping spheres (OS) method is based on the change of the molecular conformation by applying a repulsive potential dependent on the overlapping volume of the central sphere and the van der Waals spheres of neighbouring atoms. In spite of its conceptual and computational simplicity, the oS method has a disadvantage that its results depend on the radius (Rv) na the position of the central sphere. Conventionally, the center of the central sphere is situated at the geometrical center of the molecule or its molecular fragment, which was defined topologically. The new fragmentation method based on cluster analysis (Ward's method) is not deplendent on molecular topology but on molecular topograplhy. The center of the central sphere was situated at the geometrical center of the larger of two clusters, i. e. molecular fragments. The new procedure was checked on three aliphatic hydrocarbon molecules with warious degree of branching, and on three diastereomers of copper(II) bis-chelates with 1-[N-(tert-butoxycarbonyl)amino]-2-hydoxyhethylcyclopropane-1-carboxylic acid. The cluster method of fragmentation is lessd subjective and generally more efficient than the old one (based on topological fragmentation). Moreover, the procedure is suitable for automation, since the fragmentation is dependent on molecular conformation.

overlapping spheres; cluster analysis; conformational analysis; 1-aminocyclopropane-1-carboxylic acid

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