Extended Connection Table Representation

Barnard, J. M., M. F. Lynch, and S. M. Welford. 1982. Computer storage and retrieval of generic structures in chemical patents. 4. An extended connection table representation for generic structures. J. Chem. Inf. Comput. Sci. 22(3) 160-164. 

Extended Connection Table Representation molecular graph... 

Barnard, J.M. Lynch, M.F. Welford, S.M. Computer Storage and Retrieval of Generic Chemical Structures in Patents, Part 4, An Extended Connection Table Representation for Generic Structures. J. Chem. Inf. Comput. Sci. 1982, 22, 160-164. 

The internal representation of GENSAL is called ECTR (Extended Connection Table Representation). It was described first by Barnard, Welford and Lynch in... 

Extended Connection Table Representation (ECTR) Example ... 

One purpose of canonical numbering is the construction of a unique name of a compound. The canonically numbered connection table representation is uniquely defined. However, it usually contains a lot of redundancy and perceived information. The final unique name is normally a compressed form of the connection table which contains just enough information to reconstruct the connection table in its canonical form. Examples of such codes are the SEMA (stereochemically extended Morgan algorithm) name and canonical SMILES. 

The structure of each compound is stored as a connection table. A molecular models is generated for each stored structure using molecular mechanics model building such as MM2, the semiempirical method MOPAC 6.0, or specialized methods such as a recently developed extended Hiickel method. Three-dimensional structures can also be generated directly from their connection tables by structure generators (see Three-dimensional Structure Generation Automation) such as concord or CORINA. Some approaches to QSPR use only descriptors derived from the topological representation of the molecular structures, and in this case the development of three-dimensional molecular models is not necessary. 

Some types of connection table, or connectivity matrix, have been specifically designed for analysi.s using graph-theoretical techniques, and the so-called Dgundji-Ugi model of constitutional chemistry utilizes bond-electron matrices , which are able to represent free electrons and are thus of particular value in computer analysis of chemical reactions. Recently, Bauerschmidt and Gasteiger have extended some of these ideas in developing an object-oriented representation of chemical species. 

---