Theoretical determination of chromophores in the chromogenic effects of aromatic neurotoxicants

Chang Guo Zhan, David A. Dixon, Mohammad I. Sabri, Min Sun Kim, Peter Spencer

Research output: Contribution to journalArticle

38 Citations (Scopus)

Abstract

We report the first computational study of the chromophores responsible for the chromogenic effects of aromatic neurotoxicants containing a 1,2-diacetyl moiety in their oxidation metabolites. A series of ab initio electronic structure calculations was performed on two representative aromatic compounds, 1,2-diacetylbenzene (1,2-DAB) and 1,2-diacetyl tetramethyl tetralin (1,2-DATT), the putative active metabolites of the neurotoxic aromatic hydrocarbon compounds 1,2-diethylbenzene (1,2-DEB) and acetyl ethyl tetramethyl tetralin (AETT), and on the products of their possible reactions with proteins that result in chromogenic effects. The electronic excitation energies determined by three different computational approaches were found to be 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) could result from ninhydrin-like reactions, rather than the formation of pyrrole-like compounds. Our pK-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. The corresponding protonated structure has a different color as it absorbs in the blue region of the visible spectrum, and its chromogenic contribution would be significant in solution at low pH.

Original languageEnglish (US)
Pages (from-to)2744-2752
Number of pages9
JournalJournal of the American Chemical Society
Volume124
Issue number11
DOIs
StatePublished - Mar 20 2002

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Chromogenics
Diacetyl
Chromophores
Ninhydrin
Metabolites
Color
Aromatic Hydrocarbons
Pyrroles
Excitation energy
Aromatic compounds
Aromatic hydrocarbons
Electronic structure
Proteins
Oxidation
1,2-diacetylbenzene
versalide
tetralin
1,2-diethylbenzene

ASJC Scopus subject areas

  • Chemistry(all)

Cite this

Theoretical determination of chromophores in the chromogenic effects of aromatic neurotoxicants. / Zhan, Chang Guo; Dixon, David A.; Sabri, Mohammad I.; Kim, Min Sun; Spencer, Peter.

In: Journal of the American Chemical Society, Vol. 124, No. 11, 20.03.2002, p. 2744-2752.

Research output: Contribution to journalArticle

Zhan, Chang Guo ; Dixon, David A. ; Sabri, Mohammad I. ; Kim, Min Sun ; Spencer, Peter. / Theoretical determination of chromophores in the chromogenic effects of aromatic neurotoxicants. In: Journal of the American Chemical Society. 2002 ; Vol. 124, No. 11. pp. 2744-2752.
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