Vibrational analysis of derivatives of polyparaphenylene

Some new conjugated polymers are the subject of extensive studies since one found their ability to be used in the fabrication of light emitting diodes. For a purpose of optimization of such materials, a good knowledge of their electronic properties is essential. Therefore, we have studied their optical properties by means of vibrational techniques. s paper, we report on two derivatives of Polyparaphenylene : one is an alkyl chain substituted PPP and the other is a deuterated ladder polymer, which has a planar conformation. Both are soluble because of alkyl substitution on phenyl rings. We present off-resonance Raman spectra of both compounds in solid state and assign the different modes with the help of dynamical calculations based on a valence force field model. The force constants of the phenyl rings have been taken from calculations performed on PPP and a good agreement is obtained between calculated and experimental data.