Synthesis and properties of paramagnetic derivatives of linear and fused polyaromatic compounds

Paramagnetic derivatives of tolan, anthracene, and terphenyl of the A-Sp-R' type, where A is an aromatic group, R' is a stable radical center, and Sp is a spacer, were synthesized. The electronic absorption and luminescence s pectra of these compounds were examined. The introduction of the paramagnet ic dihydroimidazole fragment causes a decrease (10-500-fold) in the quantum yield of luminescence compared to emission of the individual aromatic lumi nophore. The presence of a radical center (R') in the (alkane)(.+)/(-.) A-S p-R-. radical-ionic pair leads to the disappearance or fast (nanoseconds) d amping of the magnetic effect of luminescence arising upon recombination of these pairs.