The unusual physicochemical properties of azulene and azulene-based compounds

Azulene, an isomer of naphthalene, has become one of hot chemical structures in the research field of functional materials, due to its anti-Kasha's rule emissions and unusual physicochemical properties (e.g., photophysical, electrochemical, and photoelectrochemical properties). In the past, the synthesis of azulene-based compounds is relatively inconvenient. Recently, there have been more and more reports about the synthesis strategies of the azulene-based compounds for finely tuning the physicochemical properties. In this article, we introduce several synthetic methods for kinds of azulene-based compounds which has unusual physicochemical properties. With these convenient methods and unique physicochemical properties, azulene-based compounds can be applied into many fields such as specific bioimaging, advanced molecular switches, organic field-effect transistor (OFET), organic light emitting diode (OLED), solar cells, and so forth. And these properties are also summarized here. (C) 2019 Chinese Chemical Society and Institute of Materia Medica, Chinese Academy of Medical Sciences. Published by Elsevier B.V. All rights reserved.