Self‐consistent Reaction Field Methods: Cavities

Comparison of Multistandard and TMS-Standard Calculated NMR Shifts for Coniferyl Alcohol and Application of the Multistandard Method to Lignin Dimers

“…All models were built using Cerius (version 4.9, Accelrys Inc.) and were energy minimized in the gas phase without symmetry or atomic constraints using Gaussian 03 . Subsequent frequency calculations ensured that a potential energy surface (PES) local minimum was attained during the energy minimization. , Energy minimizations and frequency calculations were performed using density functional theory (DFT) , with the hybrid density functional B3LYP − coupled with the 6-311++G(d,p) Pople-type basis set. , All single-point NMR GIAO calculations − were executed using the self-consistent reaction field (SCRF) method, applying the integral equation formalism variant of the polarized continuum model (IEFPCM) using the permittivity constants for acetone, dimethylsulfoxide (DMSO), and chloroform (CHCl 3 ) for C, while only acetone was used for H to more closely approximate experimental solvent conditions. ,, The GIAO NMR results were observed and extracted using GaussView 03…”

“…Each gas-phase, energy minimized structure of the six coniferyl alcohol conformers was then subjected to single-point GIAO − NMR calculations in a polarized continuum , of either acetone, chloroform, or DMSO using either the Hartree−Fock (HF) or B3LYP methods, − , combined with the 6-311+G(2d,p) basis set. ,, Additional single-point GIAO NMR calculations, using the mPW1PW91 hybrid density functional coupled with the 6-31G(d) basis set, in a polarized continuum of acetone, chloroform, or DMSO, were performed for each of the six MG models to determine the effect of using multiple standards for calculating NMR shifts for coniferyl alcohol, compared with those obtained from the single standard (TMS) reference method. , …”