Searching a Full Generics Database

Abstract

A hierarchy of screening methods applicable to full generic structures, including generic radical terms, is described. The most general level of description is fragment screening, which includes atom and bond centred fragments, ‘bubbled-up’ from full generic structures, where the logical relationships between fragments are retained in MUST and POSS screens. Ring systems are characterised and represented as a section of the bit string in a similar logical procedure.

A second screening method which retains the topology of a generic structure as an AND/OR tree is the reduced graph method, where the ring and non-ring components of structures are distinguished. Non-ring components are further distinguished as aggregates of carbon atoms and non-ring nodes consisting of connected heteroatoms. The nodes of a reduced graph are further characterised by a hierarchy of descriptors, ranging from an indication of the status of structural features within nodes to the most detailed description, i.e., the constituent atoms for nodes derived from specific partial structures and parameter lists for nodes derived from generic partial structures.

Finally the integration of these two screening methods is described, i.e., the inclusion of fragment and ring screens within the nodes of a reduced graph.