|Title||Conjugated oligomers incorporating azulene building blocks - seven- vs. five-membered ring connectivity|
|Publication Type||Journal Article|
|Year of Publication||2014|
|Authors||E. Amir, M. Murai, R.J. Amir, J.S. Cowart, Jr., M.L. Chabinyc, and C.J. Hawker|
The properties of isomeric azulene derivatives based on 7-versus 5-membered ring substitution were examined by the synthesis and characterization of well-defined electroactive oligomers. The substitution pattern was shown to dramatically influence solid-state, electronic and optical properties of the oligomers with acid-responsive materials only being observed when the azulenium cation could be directly stabilized by substituents in the 7-membered ring. Protonation was accompanied by a reversible color change and a strong red-shift of the absorption maximum as indicated by UV-vis studies. In addition, we show that the absorption maxima and optical band-gaps of azulenium cations can be tuned by the nature of the chromophore connected to the seven-membered ring of the azulene nucleus.