Azulene Chemistry - Journal of Chemical Education (ACS Publications)

The month's Featured Molecules illustrate some of the chemistry of a substituted azulene, a structural isomer of naphthalene...
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JCE Featured Molecules

William F. Coleman Wellesley College Wellesley, MA 02481

Azulene Chemistry November Featured Molecules The month’s featured molecules come from the paper by Charles Garner illustrating some of the chemistry of a substituted azulene (pages 1686–1688). Azulene is a structural isomer of naphthalene and differs from it in several important ways, the most obvious being azulene’s intense blue color, which arises from the S0 → S2 transition. Another unusual feature of this molecule is that its fluorescence arises from the reverse of this transition rather than from S1 → S0. Castanho has described some of the reasons behind these phenomena in this Journal (Castanho, Miguel A. R. B. J. Chem. Educ. 2002, 79, 1092–1093).

Included on the Web site this month are interactive molecular orbitals for azulene and naphthalene computed using the semi-empirical AM1 model. In order to visualize the orbitals the user must install the ActiveX version of the HyperChem Web Viewer (http://www.hyper.com/products/ Professional/WebViewer.htm). An introduction to using the viewer is available at: http://www.JCE.DivCHED.org/JCEDLib/WebWare/ collection/open/JCEWWOR004/index1.html

Fully manipulable (Chime and Jmol) versions of these and other molecules are available at the Only@JCE Online Web site: http://www.JCE.DivCHED.org/JCEWWW/Features/ MonthlyMolecules/2005/Nov

azulene 4,6,8-trimethylazulene

reaction product of 4,6,8-trimethylazulene with trifluoroacetic anhydride followed by aqueous base

1688

Journal of Chemical Education



Vol. 82 No. 11 November 2005



www.JCE.DivCHED.org