Self-Assembling Asymmetric Bisphenazines with Tunable Electronic Properties

This paper reports novel self-assembling T-shaped conjugated molecules based on asymmetric bisphenazines in which hexadecyloxy substituted bisphenazine is orthogonally fused with 1,4-bis(2-phenylethynyl)benzene. Tunability of one-dimensional (1D) self-assembly and electronic properties of the system was demonstrated by peripheral substitution with small functional groups. These functional groups (OCH 3, H, CN) progressively reduced LUMO levels as predicted by theoretical calculations and experimentally verified by cyclic voltammetry (CV). Furthermore, the morphologies of 1D assembly were greatly influenced by the substituents. While conformational flexibility of methoxy hampered successful assembly, hydrogen and cyano substitution induced the formation of rigid microstrands and flexible nanofibers, respectively, using phase transfer methods. Detailed instrumental analyses of the 1D assembled clusters including scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and X-ray diffraction (XRD) are presented. The design strategy of the new T-π-core and peripheral substitution provides a tool to control the morphology of 1D clusters with minimal structural modification of the π-core while allowing modulation of electronic properties.