Theoretical Determination of Chromophores in the Chromogenic Effects of Aromatic Neurotoxicants
- COLUMBIA UNIVERSITY
- BATTELLE (PACIFIC NW LAB)
- Oregon Health Sciences University
We report the first computational study of the chromophores responsible for the chromogenic effect of aromatic neurotoxicants containing a 1,2-diacetyl moiety in their oxidation metabolites. A series of ab initio electronic structure calculations were performed on two representative aromatic compounds, 1,2-diecetylbenzene (1,2-DAB) and 1,2-diacetyl tetramethyltetralin (1,2-DATT), the metabolites of the widely used neurotoxic aromatic hydrocarbon solvents 1,2-diethylbenzene (1,2-DEB) and acetyl ethyl tetramethyl tetralin (AETT), and products of possible reactions which could lead to chromogenic effects. The electronic excitation energies determined by three different computational approaches are all consistent with each other. The calculated results are consistent with the conclusion/prediction that the chromogenic effects of 1,2-DAB (or 1,2-DEB) and 1,2-DATT (or AETT) are due to the ninhydrin-like reactions, rather than the formation of pyrrole-like compounds. Our pKa calculations further indicate that the chromophore, i.e. the product of the ninhydrin-like reaction, showing the blue color is deprotonated in neutral aqueous solution, whereas the corresponding protonated structure has a different color and its chromogenic contribution could be significant in solution at lower pH. In acidic solutions, the protonated structure could be dominant and the chromophore could show a different color.
- Research Organization:
- Pacific Northwest National Lab., Richland, WA (US)
- Sponsoring Organization:
- US Department of Energy (US)
- DOE Contract Number:
- AC06-76RL01830
- OSTI ID:
- 15001227
- Report Number(s):
- PNNL-SA-34799; KP1301030; TRN: US200323%%370
- Journal Information:
- Journal of the American Chemical Society, Vol. 124, Issue 11; Other Information: PBD: 20 Mar 2002
- Country of Publication:
- United States
- Language:
- English
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