PHOTOPHYSICS OF CARBAZOLE-CONTAINING SYSTEMS - 3 FLUORESCENCE OF CARBAZOLE-CONTAINING OLIGOETHERS IN DILUTE-SOLUTION

Fluorescence techniques, including quenching and anisotropy measuremen ts, have been used to study the photophysical behavior of the carbazol e-based oligoethers poly{9-(2,3-epoxypropyl)-carbazole}, PEPCz, and po ly{1,2-epoxy-6-(9-carbazolyl)-4-oxahexane}, PECzOH, and their model co mpounds, in dilute fluid solutions in THF. These compounds show no evi dence of excimer formation under these conditions and their fluorescen ces exhibit first-order decay behavior regardless of the degree of pol ymerization of the oligomer. Both steady-state and time-resolved aniso tropy measurements upon dilute, glassy solutions show that intramolecu lar energy migration occurs in the oligomers. Fluorescence quenching e xperiments, using both dimethylterephthalate and oxygen as quenchers, produced evidence which supports the supposition that in the absence o f excimer trapping sites, intramolecular energy migration will be enco uraged in dilute fluid solutions of the oligoethers. Unfortunately, th e fluorescence quenching data did not permit evaluation of the extents of energy migration in the various polymers or the relative efficienc ies with which migration occurs in the two different types of oligoeth er. This limitation would appear to be a general feature of fluorescen ce quenching measurements, despite their frequent adoption, in the pas t, in studies of energy migration in polymers.