Azulene Chemistry

The month's featured molecules come from the paper An Azulene-Based Discovery Experiment: Challenging Students To Watch for the "False Assumption" 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.
Azulene Chemistry   
(Interactive Simulation (1))