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ACD/Labs 5th Annual European Users' Meeting 2004 (EUM)
Elucidating Chemical Structures Using ACD/Labs' NMR Software
Brent Lefebvre, Gavin Shear, Mikhail Elyashburg, Kirill Blinov, Arvin Moser
Abstract
A common failing among Computer Aided Structure Elucidation (CASE) products is the inflexibility built into the rigid decision trees that are necessary in software design. When an elucidation expert undertakes an elucidation manually, there is an inherent flexibility in the data that is used for interpretation, and the situations that can be encountered and dealt with successfully. This is not completely unexpected as it is commonly accepted that the ability of an expert human to deal with an unexpected event is much better than that of a computer. Software can rarely deal with "unexpected" phenomena; this ability would have to reside in a set of instructions somewhere in the code of that software and that then effectively eliminates the "unexpected" nature of the event! For this reason, CASE systems have traditionally not lived up to the expectation of a truly helpful algorithm for solving structures. Here will be presented a system that finally dispenses of this image.
ACD/Structure Elucidator was designed to accommodate a large variety of input data and discrepancies in that data set that would often cripple the traditional CASE systems. This is accomplished through a significant number of unique procedures. In this presentation, what will be shown and discussed are some of the most unique and innovative features of this CASE system. In particular, topics will include: data consistency checking to determine if a set of input data is suitable for an elucidation attempt; 2D correlation contradiction resolution to automatically resolve any discrepancies in the set of 2D peak connectivities that are offered as input to the process; fuzzy-logic structure generation to allow the elucidation of structures even when unresolved contradictions exist; and rank ordering of the result structures by many different criteria to help the user determine which one is the correct answer.
These procedures will be presented first by discussing the problems these features were intended to solve, the concept of the design including algorithmic details, and then how these procedures are executed by the user in the course of an elucidation. Numerous examples will then be presented that illustrate the flow of the procedures and the results that can be obtained under these challenging circumstances.
Download the presentation in MS PowerPoint (484 Kb ZIP file) or Adobe Acrobat format (632 Kb PDF file).
Relevant Products: Structure Elucidator
Relevant Solution: Structure Elucidation
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