Structural Analysis with NMR Chemical Shift calculation

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Conformational analysis in solution is indispensable for understanding of physical and chemical properties of organic compound. While NMR techniques such as distance-dependent nOe and torsion-dependent ^3JHH coupling constants were used extensively, it is not always satisfactory. We have recently developed chemical shift simulation, which utilizes the substituent induced shifts (SIS) of polar functional groups. This simulation method can calculate the induced shift of a near-by proton from a polar substituent. To widen the applicability of this unique method for conformational analysis, we have succeeded to obtain the SIS parameters of the secondary amine group (C-NH-C) which is ubiquitous in organic compounds. Similar procedure using androstanone skeletons was applied to obtain the magnetic anisotropy of naphthalene ring. The successful reproduction of the substitution induced shifts clearly indicates that the combination of the molecular dynamics and the chemical shift simulation method play an important role in the development of the conformational analysis of the dynamic structure of the flexible molecules. The dynamic structure of inclusion complexes was also successfully analyzed by the combination of the molecular dynamics and the chemical shift simulation.