Synthesis and properties of alternating alicyclic polyimides having fluorescent moieties

A series of alternating copolyimides (altPIs) having highly blue fluorescing 9,10-diphenylanthracene units were synthesized and the photoluminescence of the altPIs were investigated. The altPIs were prepared by sequential addition of two diamines to a solution of spiroalicyclic tetracarboxylic dianhydride, rel[1R,5S,6R]-3-oxabicyclo[3.2.1]octane-2,4-dione- 6-spiro-3'-(tetrahydrofuran-2',5'-dione) (DAn), on the basis of the unique regioselective ring opening reactivity of DAn to the aromatic amines. The alternating structure of the polyimides was confirmed by comparison of its ¹ H-NMR with that of the corresponding random counterparts. The altPIs showed grass transition temperature higher than 240°C. A 5% weight loss temperature was in a range of 335 to 376°C. The polyimides showed blue fluorescence (λ _max = 435 to 436 nm) in DMSO solution with a fluorescence quantum yield of 0.64 to 0.77. In the film state, although small red shift was observed compared to the solution state, the altPIs gave blue emission (λ _max = 437 to 447 nm).