PHOTOPHYSICAL INVESTIGATION OF LANGMUIR-BLODGETT-FILMS OF AMPHIPHILICDISCOTIC PENTA-ALKYNES

Amphiphilic discotic pentakis(arylethynyl) benzene compounds 1 and 2 c ontaining an enlarged aromatic core functioning as a chromophoric pi-e lectron system were studied with regard to their photophysical propert ies within Langmuir-Blodgett (LB) films. The results obtained from ste ady-state absorption as well as fluorescence excitation and emission m easurements will be discussed with regard to interchromophoric interac tions in the LB films. Time-resolved fluorescence investigations revea led the formation of a ground-state complex as well as excimer formati on. Thermal treatment causes irreversible destruction of the LB film s tructure of the discotic amphiphiles. Within droplets the reorganizati on of the original nematic-discotic (N-D) mesophase of the bulk materi als was found for the alcohol 2 as indicated by a Maltese Cross textur e, whereas the acid 1 remained isotropic.