SPECTROSCOPIC CHARACTERIZATION AND LANGMUIR-BLODGETT-FILMS OF N,N-SYMMETRICAL DIALKYL-3,4/9,10-PERYLENEBIS(DICARBOXIMIDE)S

The electronic and vibrational spectra of N-R-N'-R-symmetrical dialkyl-3,4:9,10-perylenebis(dicarboximide)s (R = C5H11, C6H13 and C8H17) are reported. Langmuir monolayers were prepared and surface pressure-area isotherms were measured for three non-amphiphilic molecules. Langmuir-Blodgett (LB) films of mixed layers only were fabricated on solid substrates. Fundamental vibrational frequencies were observed using surface-enhanced resonance Raman scattering, transmission and reflection-absorption (RAIRS) Fourier transform infrared spectroscopy. The molecular orientation in the LB films was established from the transmission and RAIRS spectra. Molecular aggregation is reduced by the presence of bulky alkyl substituents. The adsorption of electron acceptor molecules and its effect on the fluorescence yield are also reported.