Synthesis and optical and electrochemical properties of novel polyethers containing isolated distyrylbenzene derivatives and side-aromatic 1,3,4-oxadiazole chromophores

New polyethers (P2, P4) with isolated emitting distyrylbenzene derivatives and pendant aromatic 1,3,4-oxadiazole chromophores have been prepared by th e Horner-Wadsworth-Emmons olefination reaction. Polyethers P1 and P3 withou t oxadiazole groups have also been synthesized for comparison. The reduced viscosities were about 0.20-0.33 dL/g, and the solubility in organic solven ts increased with a number of side methoxy or ethoxy substituents in the di styrylbenzene section. Absorption spectra showed two peaks at 371-388 and 3 04 nm that corresponded to the pi-pi* transition of the conjugated distyryl benzene derivatives and aromatic oxadiazoles, respectively. The band gaps w ere at 2.76-2.85 eV, which were calculated from onset absorption in the fil m state. The photoluminescence (PL) maxima were at 459-469 nm, indicating t hat they are blue-emitting materials, and the relative PL quantum efficienc ies were 0.62-0.77 and 0.23-0.40 in solution and the film state, respective ly. Cyclic voltammetric investigations demonstrated that oxadiazole moietie s decrease the barrier of electron injection but also retard hole injection . (C) 2001 John Wiley & Sons, Inc.