In the Laboratory edited by
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
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Vol. 82 No. 11 November 2005
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www.JCE.DivCHED.org
