Azapyrene-based fluorophores: synthesis and photophysical properties

Azapyrenes are the nitrogen isosteres of pyrene. Based on theoretical and experimental studies, electron-acceptor azapyrene domains may be considered as convenient scaffolds for constructing a large variety of "push-pull" π-conjugated chromophores with pronounced ICT properties. Over the past decade, due to the unrelenting interest in functional materials and modern methodologies such as cross-coupling, peri -annulation, direct C-H-functionalization, etc. , methods for the synthesis of aryl(alkyl) K-functionalized azapyrenes and other derivatives have been developed, and their photophysical and electrochemical properties have been studied. This short review aims at critical analysis of the best known/modern methods for the preparation of functionalized azapyrene derivatives, as well as an assessment of their photophysical/electrochemical properties in comparison with the structural and electronic properties of the parent pyrene. The latest methods for the preparation/functionalization of azapyrenes, and their photophysical/electrochemical properties and possible applications are overviewed.