COMP 42 |
| Information on atom connectivity of hydrogen-depleted formulas for organic compounds can be provided by various topological indices, which use different graph invariants for this purpose. If one wishes to include information on stereochemistry, more sophisticated approaches are needed. Topological indices are based on local (vertex) graph invariants, LOVIs, which can be integers or real numbers. For a given structure, these LOVIs are assembled into one numerical value (the topological index, TI) which again can be an integer or a real number. So far, no TI was designed which would be able to be in a one-to-one correspondence with a chemical structure; there are always several structures that correspond to a numerical value of a TI, giving rise to the degeneracy of TIs. The higher the degeneracy, the lower the discrimination ability of the TI. However, real-number LOVIs and real-number TIs have lower degeneracy than integer-number analogs. For such analogs and a few real-number TIs with low discrimination ability, there exist algorithms for finding all possible structures associated with a given TI; this is the so-called “inverse problem” that arises when one wishes to test structures fitting in a QSAR, QSTR or QSPR “window” or interval of biological activity, toxicity, or value of a physical property, respectively. A brief review will be presented for TIs of high and low degeneracy, for TIs that have algorithms for the corresponding inverse problems, and for TIs which offer promise that they could be associated with biological, physical or chemical properties without the possibility of retrieving information on the chemical constitution of the corresponding compounds. |
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Safe Exchange of Chemical Information: Can Relevant Chemical Information be Exchanged Without Disclosing Chemical Structures?
1:20 PM-5:20 PM, Sunday, 13 March 2005 Convention Center -- Room 4, Oral
Division of Computers in Chemistry |