Substituent effect on the electronic and assembling properties of asymmetric phenazine derivatives

Currently, one-dimensional (1-D) nanostructures have drawn much interest because of their potential applications for nanoscale optoelectronic devices. Self-assembly (SA) based on pi-conjugated systems through various intermolecular interactions has been widely used to produce 1-D nanostructure. Morphology of the assembled structures can be modified by incorporating substituents, which provide additional secondary interactions. Meanwhile, those substituents also influence the electronic properties of the molecules. Previous studies have made little effort to systematically study subsistent effects on both electronic and SA properties.;The primary objective of this research is to generate controllable 1-D structures through SA, and to provide a fundamental understanding of how different peripheral substituents bonded to a pi-core influence the electronic and assembling properties of the molecules. A series of asymmetric phenazine derivatives containing different functional groups were designed and synthesized in order to investigate the halogen effect, position effect and the alkoxy chain length effect. The electronic properties were studied by UV-vis spectroscopy, fluorescence spectroscopy, and cyclic voltammetry (CV). The experimental results of the systems' electronic properties are compared with the theoretical calculations. The SA properties were extensively investigated by polarized optical microscopy (POM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), single crystal X-ray crystallography, and X-ray diffraction (XRD).