Polaron Delocalization in Ladder Macromolecular Systems

Organic macromolecules with conjugated building blocks have been the focus of extensive
research that is motivated, in part, by the potential to create optical and electronic devices. We have shown
that palladium-catalyzed amination can assemble triarylamine ladder materials with extended structures.
Two ladder macromolecules have been prepared in high yields by a series of twelve or sixteen C−N coupling
reactions. Studies of the electronic and optical properties of neutral and oxidized forms of the ladder
structures were conducted. The optical and electronic properties of the ladder systems are compared to
those of the linear tetra-phenyl-p-phenylenediamine as well as the tetra-p-anisyl-p-tetraazacyclophane.
The electrochemistry of the ladder systems consists of a multiwave voltammogram with a relatively low
first oxidation potential. Electron paramagnetic resonance spectroscopy of the ladder systems suggests
the presence of a large density of delocalized polarons. Linear absorption measurements of the chemically
oxidized ladders revealed both polaron and intervalence absorption bands. Steady-state and time-resolved
fluorescence measurements were also carried out to characterize the dynamics in these novel systems.