Other types of linear molecular descriptors include computer-readable formats, such as Wiswesser Line Notation (WLN), SYBYL ®, SMILES (Daylight Chemical Information Systems), and InChI codes. The list of rules restricting the names of compounds that are supported by this program is published on the home page of the software vendor. NameExpert TM, a product of ChemInnovation, converts IUPAC names to chemical structures, but the program cannot handle the names of certain specific classes of molecules, such as names of element-organic compounds. As with naming, drawing of polycyclic and abnormal valence element molecules is the most difficult task, even for the latest versions of the software. The reverse task-chemical structure graph generation from the chemical name-has it set of problems too. Ambiguity in IUPAC naming complicates searching and chemical identity comparison. In addition, chemical names generated by various computer programs are often not unique. In many cases the existing name-generating programs cannot process some classes of compounds, such as cage structures or molecules with abnormal valence elements. Chemical names are relatively long and have sophisticated formats, thus impeding computer structure recognition. IUPAC and CAS names are the most understandable notation for a chemist, but their use in databases or as Internet descriptors is a complicated task. Two approaches exist for representation of molecular structures as linear descriptors-chemical names or computer-readable codes.ĬAS and IUPAC nomenclature are examples of the chemical name approach. This method of coding reduces net traffic, allows work with a chemical structure as an object, for example, to rotate three-dimensional (3D) structure in space, and allows the structures to be edited in Web interfaces of chemical databases.

An alternative method entails use of special chemical applets or plug-ins capable of rendering chemical structure information encoded in chemical descriptors.

Although chemical structures on the Web can be presented as bitmap objects (in GIF, JPEG, or PNG formats), this method of representation is not optimal. Their role has increased significantly with the advent of the Internet. Linear molecular descriptors are frequently used for storing, retrieval, and presentation of chemical information.

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