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Rationalizing nuclear overhauser effect data for compounds adopting multiple‐solution conformations
Author(s) -
Forster Mark J.,
Mulloy Barbara
Publication year - 1994
Publication title -
journal of computational chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.907
H-Index - 188
eISSN - 1096-987X
pISSN - 0192-8651
DOI - 10.1002/jcc.540150206
Subject(s) - conformational isomerism , nuclear overhauser effect , chemistry , coupling constant , relaxation (psychology) , population , computational chemistry , derivative (finance) , proton , nuclear magnetic resonance , nuclear magnetic resonance spectroscopy , stereochemistry , molecule , physics , quantum mechanics , organic chemistry , psychology , social psychology , demography , sociology , financial economics , economics
An algorithm is described for refining the populations of a set of multiple‐solution conformers using experimental nuclear Overhauser effects (nOes). The method is based upon representing the effective relaxation matrix for the set of interconverting proposed conformers as a linear combination of relaxation matrices (LCORMs) due to each conformer. The conformer population derivative of the nOe is derived from a Taylor series expression for the calculated nOe. This derivative may then be used in a standard nonlinear least‐squares refinement procedure. The LCORM nOe procedure is tested using a monosaccharide system, 1‐ O ‐methyl‐α‐ L ‐iduronate, that is known to exhibit conformational variability. The measured nOes for this system are used to refine the populations of a set of three static conformers, namely, the 1 C 4 , 4 C 1 , and 2 S 0 ring conformers. The populations thus derived are compared to those previously obtained using nuclear magnetic resonance proton‐proton coupling constant information. Two possible extensions to the method are discussed: The first uses combined nOe and coupling constant data while the second removes the restrictions that the conformers used for fitting be rigid entities. © 1994 by John Wiley & Sons, Inc.