Lars Blankenburg

Investigation on the synthesis and reaction of new aniline derivatives in Pd-catalyzed cross-coupling

New aniline derivatives have been synthesized to investigate the possibility of polymer synthesis by Pd-catalyzed cross-coupling. Dialkylation and ethynylation of the aniline monomers and the synthesis of new monomers 2, 3, and a 2,2′-bipyridine-containing oligomer 4 could be realized.

Design and synthesis of ruthenium(II)-bipyridyl-containing polymers

A series of novel π-conjugated polymers containing ruthenium bipyridine complexes have been synthesized by a cross-coupling reaction and characterized. These polymers exhibit absorption maxima at around 330 - 350 nm (π-π*) and 460-500 nm (MLCT) respectively. They are soluble in common organic solvents and all polymers can be converted into transparent films. We investigated the influence of different donating and acceptor diethynylarenes on the UV/Vis spectra. The oxidation potentials, which have been measured by cyclic- and square-wave voltammetry, show a typical Ru2+/3+ exhibiting at around + 1.26 V vs. SCE and an additional peak for triphenylamine containing polymers (+ 1.07 V C4c). The polymers were further characterized with photoluminescence measurements. When excited at 442 nm (C2), the polymer showed an emission peak at 690 nm. This peak is attributed to the MLCT states.

New oligomers with alternating phenylene ethynylene pyridinylene structure

The new 1,4-diethynyl aniline derivatives 1a and 1b were synthesized and successfully used in a Sonogashira cross-coupling reaction with 2,5-dibromopyridine. While the alternating oligomer 2a is soluble in THF or chloroform, oligomer 2b with a N, N-dioctylgroup in the phenylene repeating unit is insoluble in organic solvents. A possible explanation can be given by strong intermolecular interactions between pyridine and the dialkyl substituted aromatic ring. The absorption maximum of 2a is at 380 nm.