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@ARTICLE{Berns:59679,
      author       = {Berns, A. E. and Bertmer, M. and Schäffer, A. and Meier,
                      R. J. and Vereecken, H. and Lewandowski, H.},
      title        = {{T}he 15{N}-{CPMAS} spectra of simazine and its
                      metabolites: measurements and quantum chemical calculations},
      journal      = {European journal of soil science},
      volume       = {58},
      issn         = {1351-0754},
      address      = {Oxford [u.a.]},
      publisher    = {Wiley-Blackwell},
      reportid     = {PreJuSER-59679},
      pages        = {882 - 888},
      year         = {2007},
      note         = {Record converted from VDB: 12.11.2012},
      abstract     = {DFT calculations are a powerful tool to support NMR studies
                      of xenobiotics such as decomposition studies in soil. They
                      can help interpret spectra of bound residues, for example,
                      by predicting shifts for possible model bonds. The described
                      bound-residue models supported the hypothesis of a free
                      amino side chain already suspected by comparison with the
                      experimental data of the standards. No match was found
                      between the calculated shifts of amide bondings of the amino
                      side chains (free or substituted) and the experimental NMR
                      shifts of a previous study. In the present paper,
                      first-principles quantum chemical calculations were used to
                      support and check the interpretation of the 15N cross
                      polarization-magic angle spinning nuclear magnetic resonance
                      (15N-CPMAS NMR) spectra of simazine and its metabolites.
                      Density functional theory (DFT) calculations were performed
                      using Gaussian 03 and the nuclear magnetic shielding tensors
                      were calculated using the Gauge-Independent Atomic Orbital
                      (GIAO) method and B3LYP/6–311+G(2d,p) model chemistry.
                      Good agreement was reached between the calculated and
                      measured chemical shifts of the core nitrogens and the
                      lactam and lactim forms of the hydroxylated metabolites
                      could be clearly distinguished. The calculated spectra
                      showed that these metabolites exist preferentially in the
                      lactam form, an important fact when considering the possible
                      interactions of such hydroxylated metabolites with the soil
                      matrix. Although the calculated bound-residue models in the
                      present study only partly matched the experimental data,
                      they were nevertheless useful in helping to interpret the
                      experimental NMR results of a previous study. To get a
                      better match between the calculated and the measured shifts
                      of the side-chain nitrogens the calculations need to be
                      further developed, taking into account the influence of
                      neighbouring molecules in the solid state. Altogether,
                      quantum chemical calculations are very helpful in the
                      interpretation of NMR spectra. In the future, they can also
                      be very useful for the prediction of NMR shifts, in
                      particular when it is not possible to measure the
                      metabolites due to a lack of material or in cases where
                      practical experiments cannot be conducted.},
      cin          = {ICG-4 / JARA-ENERGY / JARA-SIM},
      ddc          = {630},
      cid          = {I:(DE-Juel1)VDB793 / $I:(DE-82)080011_20140620$ /
                      I:(DE-Juel1)VDB1045},
      pnm          = {Terrestrische Umwelt},
      pid          = {G:(DE-Juel1)FUEK407},
      shelfmark    = {Soil Science},
      typ          = {PUB:(DE-HGF)16},
      UT           = {WOS:000248479300003},
      doi          = {10.1111/j.1365-2389.2007.00927.x},
      url          = {https://juser.fz-juelich.de/record/59679},
}