دانلود مقاله با موضوع تخصیص تغییر شیمیایی 13C NMR بنزو[a]پیرنهای نیتراتی بر اساس تکنیک های دو بعدی
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موضوع به انگلیسی:13C NMR chemical shift assignments of nitrated benzo[a]pyrenes based on
two-dimensional techniques and DFT/GIAO calculations
بخشی از متن:Nitrated benzo[a]pyrenes are known to be mutagenic, carcinogenic and teratogenic to bacterial and animal
cells. For differentiation of isomers and environmental analytical trace studies, spectroscopic information is
necessary. The present studies report the 13C NMR spectra of 1‐, 3‐ and 6‐nitrobenzo[a]pyrene measured in
CDCl3. Complete 13C NMR assignments based on 2D NMR spectroscopy (HMQC and HMBC) were carried
out. Further, the computation of fifty 13C chemical shifts of 1‐, 3‐, and 6‐nitrobenzo[a]pyrenes by using
GIAO B3LYP/6‐311+G(d,p)//B3LYP/6‐31+G(d), 6‐31+G(d,p), 6‐311+G(d), 6‐311+G(d,p), 6‐311G(d,p)
levels of theory was investigated. For 1‐, 3‐ and 6‐NBaP the calculated chemical shifts δcalc versus δexpt plots
of chemical shifts fall on a linear correlation line with r2 > 0.90. The GIAO B3LYP/6‐311+G(d,p)//B3LY
P/6‐311G(d,p)level of theory was found to yield chemical shifts in good agreement with experiment with
r2 > 0.90. The most expensive method (larger basis set) has provided the best agreement with the experiment.
It is therefore important to continue to seek computational methods that can predict precise chemical shifts in
nitrated or related compounds.
