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Prediction of 13C chemical shifts in methoxyflavonol derivatives using MIA-QSPR

Mohammad Goodarzi1, Matheus P Freitas, Teodorico C Ramalho

  • 1Department of Chemistry, Faculty of Sciences, Azad University, Arak, Iran.

Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
|August 4, 2009
PubMed

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The position of the absorption signal of a sample is reported relative to the position of the signal of tetramethylsilane (TMS), which is added as an internal reference while recording spectra. The difference between the absorption frequencies of the sample and TMS (in Hz) is divided by the spectrometer operating frequency (in MHz) to obtain a dimensionless quantity called the chemical shift. It is reported on the δ (delta) scale and expressed in parts per million.
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In an NMR sample, precise measurement of the absolute absorption frequencies of nuclei is difficult. A standard internal reference compound is added, and the frequency difference between the reference signal and sample signals is measured.
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¹H NMR: Complex Splitting

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