NMR Research Today is a free monthly online journal that collates and summarizes the latest research about NMR, including details on nuclear magnetic resonance, structural determination, techniques.

A computationally feasible quantum chemical model for 13C NMR chemical shifts of PCB-derived carboxylic acids.

Kolehmainen E, Tuppurainen K, Lanina SA, Sievänen E, Laihia K, Boyarskiy VP, Nikiforov VA, Zhesko TE

Department of Chemistry, University of Jyväskylä, P.O. Box 35, FIN-40014, Finland. ekolehma@cc.jyu.fi

Two quantum chemical models have been derived for the prediction of 13C NMR chemical shifts of novel PCB acids obtained from PCBs by catalytic carbonylation. 13C isotropic shielding constants were calculated employing the GIAO (gauge-independent atomic orbital) method with density functional theory (DFT). The best results were obtained by cluster calculations, which took the solvent effects into account properly. In this approach, a solvent molecule (acetone) was attached by a hydrogen bond to every hydrogen atom present in a PCB acid, and the geometry of the molecular cluster was optimized employing the AM1 method. For 158 chemical shifts, the cross-validated standard error was 2.8 ppm and the cross-validated correlation coefficient was 0.94.

Published 5 December 2005 in Chemosphere, 62(3): 368-74.
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