| Azulene
Chemistry The
month’s featured molecules come
from the paper by Charles
Garner illustrating some of the
chemistry of a substituted azulene.
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 be using a Windows operating
system and Internet Explorer 6.0 or
later with the ActiveX version of the HyperChem
Web Viewer installed. An introduction
to using the viewer is available in JCE WebWare.
In addition to static images, two
fully manipulable versions (Jmol, MDLChime)
of these molecules appear below. (The
Jmol versions may take a few extra
seconds to load, based on the speed
of your Internet connection.) |
