Nitroxide-Mediated Polymerization of Styrenic Triarylamines and Chain-End Functionalization with a Ruthenium Complex: Toward Tailored Photoredox-Active Architectures

The preparation of redox-active polymers and the chain-end functionalization with one ruthenium complex was investigated in detail. A series of substituted monomers, i.e., styrenic triarylamines bearing methyl, fluoro, or methoxy substituents, were prepared by a one-pot Hartwig–Buchwald coupling. The nitroxide-mediated polymerization (NMP) was studied by variation of the functional initiators, the monomer-to-initiator ratios, and the solvent. The kinetic analysis of the prototypical methyl-substituted triarylamine shows the controlled polymerization up to 75% conversion, but a considerable decrease of the polymerization rate was observed during the course of the reaction. Both chain-end functionalities of the purified oligomers were subsequently utilized, i.e., the nitroxide to serve as a macroinitiator for an additional NMP step and the chloromethyl group to introduce one ruthenium complex at the chain terminus. The products were analyzed in detail by size-exclusion chromatography, NMR spectroscopy, and mass spectrometry. The optical and electrochemical properties of the prepared poly(triarylamine)s show the application potential as charge transport materials in conjunction with the photoactive ruthenium complex.