Structures Systems Molecular Design Limited

To cover the specialized area of chemical structures in detail, authors could provide only cursory coverage of mathematical expressions and tabular material. Many of the scientific word processing packages that I mentioned and some software the book discusses in detail (especially ChemText from Molecular Design Limited) will handle scientific and graphics material other than chemical structures. This book does not cover well-known graphics systems that handle chemical structures or chemical reactions these systems are already well-documented (6, 7). 

The next step up in integration places as much information as possible in the chemical structure or reaction DBMS. For example, Molecular Design Limited s MACCS system has been used to store structures, reactions, biology, spectra, inventory, and document index information. This approach provides a good degree of data integration but suffers from poor performance for large databases. Additionally, the retrieval capabilities of the structure DBMS are inadequate for certain types of information. 

Once many in-house, chemical structure data bases had been built, the users began to realize that it was more efficient to use commercially-available structure handling software for structures alone (or structures and a minimal amount of related property data) and to take advantage of data base management systems to handle property data. Molecular Design Limited (MDL) and Telesystemes modified their MACCS and DARC software, respectively, to allow for the appropriate interfacing of structures and data. 

Computational chemists have developed several remarkably powerful and reliable computer codes, capable of describing the relative stability of various conformations of macromolecules, and details of the electronic structure of molecules of more modest size ( 1). The properties of molecules which can be obtained by use of these programs correlate with important features of chemical reactivity and the properties of materials. Molecular design, in pharmaceuticals, photochemistry, and general materials science can be made much more efficient by the routine use of these computational systems. However, their use is at present not widespread it is limited to a few large chemical companies. 

One of the few examples of commercially available retrieval systems encompassing both compounds and reactions is Molecular Design s microcomputer-based ChemBase system. It saves molfiles (molecular structure files) separately from its reaction file without any elaborate linkages between the files. This makes it rather difficult to move information between the files and requires the conversion of a molfile to move it in or out of a reaction file. Additionally, searching a compound structure for where it appears in a reaction is not a simple operation. Lastly, reaction sites are neither identified nor searchable. These limitations could be overcome if the reaction site could be associated with the molfiles or reaction files stored for searching. 

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