Optimizing Protocols for Carbohydrate NMR Chemical Shift Computations
The spectroscopic analysis of cellulose is experimentally challenging while computationally accessible with recent developments in NMR code. However, prior to using density functional theory to calculate the NMR chemical shifts of cellulose, smaller, sugar-like molecule systems need to be benchmarke...
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| Format: | Others |
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Scholar Commons
2016
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| Online Access: | http://scholarcommons.usf.edu/etd/6273 http://scholarcommons.usf.edu/cgi/viewcontent.cgi?article=7469&context=etd |
| Summary: | The spectroscopic analysis of cellulose is experimentally challenging while computationally accessible with recent developments in NMR code. However, prior to using density functional theory to calculate the NMR chemical shifts of cellulose, smaller, sugar-like molecule systems need to be benchmarked against experimental values. The quantum mechanical / molecular mechanical (QM/MM) calculations presented herein utilize six test systems: ethanol, pyridine, pyrrolidine, pyrrole, myo-inositol and scyllo-inositol in conjunction with the reference tetramethylsilane used to scale the calculated isotropic shielding tensors to relative chemical shifts. The effect of solvent on calculated NMR chemical shifts has also been investigated with regard to quantity of solvent surrounding the molecule of interest. Lastly, a mixed basis approach with two quantum regions has additionally been employed to investigate the effects of the number of basis functions on the relative cost of QM/MM NMR calculations. |
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