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Synthesis and Photophysical Characterization of New Oligophenylenevinylenes

Mendonça, A. ; Charas, A. ; Paolo, R. ; Lanzani, G. L. ; Morgado, J.

Synthesis and Photophysical Characterization of New Oligophenylenevinylenes, Proc IUPAC Symposium on Photochemistry, Coimbra, Portugal, Vol. -, pp. - - -, July, 2012.

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Abstract
Conjugated systems, encompassing both polymers and low molecular compounds, have been widely studied over the last years. The interest derives not only from their potential applications in a wide range of electronic and optoelectronic devices and systems, but also from the various photophysical phenomena they exhibit, such as amplified stimulated emission and optically pumped lasing. Chemists’ ability to modify their molecular structure and thereby changing their properties, both in solution and solid state, has been used to obtain a deeper understanding of the photophysical processes taking place after photo- or electrical excitation.
In this communication we report on the synthesis and characterization of three new oligophenylenevinylenes, whose structures are shown in Fig. 1. The three structures were chosen to study the effect of end capping groups’ flexibility and the presence of an electron-accepting moiety. Aside CW characterization, their fluorescence lifetimes at the picosecond resolution were also determined. It is interesting to note the nearly quantitative fluorescence emission of TPA-Phoe-TPA, while the similar compound with the more rigid carbazole end groups shows a lower fluorescence quantum yield. Amplified spontaneous emission was also observed for these two oligomers. The parent compound having a benzothiadiazole group has an emission spectrum that is significantly red-shifted and a lower fluorescence efficiency.