Synthesis, photophysical characterization and applications of N-heterocyclic based multibranched donor-acceptor derivatives

Abstract

Organic N-heterocyclic based donor-acceptor derivatives have drawn great attention due to their various potential applications in organic light emitting diodes,1 sensors,2 lasers3 and biomedical applications.4 The precise tuning of donor-acceptor interactions allows the modification of their electron affinities and their ionization potentials, giving rise to new functional material with tunable band gaps and, consequently, having very different electronic and optical properties. In this regard, developing organic π conjugated molecules with donoracceptor or donor-π-acceptor structures based on N-heterocyclic molecules is fascinating due to their unique optical and electronic properties. It is well known that optical and electronic properties of donor-acceptor systems are dependent on excited state dynamics involving intramolecular charge transfer state (ICT). Therefore, the photophysical properties such as the emission, fluorescent quantum yield, fluorescence lifetime, and phosphorescent emission of organic -conjugated chromophores highly depend on the ICT state of chromophores. It is possible to tune the nature of the ICT state by manipulating the molecular structure of donoracceptor systems, introducing different substituents, changing the reduction and oxidation potential of acceptor and donor, respectively, changing the length of bridges, and changing the geometry of chromophores.