Picosecond structural relaxation of abietic acid based amine end capped para-phenylenevinylene trimers in solution.

The synthesis and photophysical properties of six new abietic acid based amine end-capped p-phenylenevinylene trimers (AECPV3) in their lowest excited singlet states are presented. The AECPV3 compounds show a large red-shift of both the absorption (25-30 nm) and emission (37-42 nm) maxima with respect to those of the corresponding trimers. Picosecond time-resolved fluorescence data reveal the presence of a fast conformational relaxation process (40-62 ps) of the initially excited compounds, leading to more planar conformers. The conformational relaxation time is proportional to the volume of both the side chain and the amine groups.