Photophysical properties of fluorescent polymers containing 1,10-phenanthroline-3,8-ylene and diethinylenebenzene units and their model compounds: A comparison to 2,2 '-bipyridine analogues

Investigation of the absorption and emission spectra (stationary and time-r esolved) of phenanthroline based polymers shows that the enforcement of a c isoid geometry in the bipyridine unit of the main chain via an ethenylene b ridge does not significantly change the spectral and the deactivation behav iour. In close analogy to similar polymers, containing bipyridine units, th e conjugation length in these polymers does not exceed ca. two chromophore units. At low temperatures, the model compounds show an additional, bathoch romically shifted, intense luminescence with an increased lifetime which ca n be interpreted as an excimer (or aggregate) fluorescence. In addition, br oad, superimposed emission bands arising from various aggregated species ar e observed. The relative intensity of these bands depends on the temperatur e processing occurring during cooling. Intersystem crossing is an insignifi cant deactivation channel.