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United States Department of Agriculture

Agricultural Research Service

Title: NBO analysis and vibrational frequencies of tautomers of citrinin by density functional theory)

Author
item Appell, Michael
item Moravec, David
item Bosma, Wayne

Submitted to: Meeting Abstract
Publication Type: Abstract only
Publication Acceptance Date: 3/31/2011
Publication Date: 3/31/2011
Citation: Appell, M.D., Moravec, D., Bosma, W.B. 2011. NBO analysis and vibrational frequencies of tautomers of citrinin by density functional theory. Meeting Abstract.

Interpretive Summary:

Technical Abstract: Citrinin is a toxic polyketide contaminant of a number of agricultural commodities, notably Monascus-fermented red rice. Detailed structures and electronic properties of three tautomeric forms of citrinin were investigated using density functional theory calculations at various extended basis sets and levels of theory. The p-quinone and o-quinone tautomers possess similar energies, and the energetic preference is basis set dependent. A carboxylic acid enol tautomer is stabilized through intramolecular hydrogen bond interactions, and within 2.4 kcal/mol at the B3LYP/6-311++G(d,p) level of theory. Despite differences in bond nature and connectivity of the tautomers, Natural Bond Orbital (NBO) analysis revealed that the tautomeric forms share similar natural charges and natural election configurations. Vibrational assignments were made on frequencies calculated at the B3LYP/6-31G(d,p) level. Results for the p-quinone and o-quinone tautomers compared favorably with published spectra.

Last Modified: 8/24/2016
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