Preparation, Photo-luminescence and Electro-Luminescence Behavior of Langmuir−Blodgett Films of Bipyridylrhenium(I) Surfactant Complexes

Several bipyridylrhenium(I) surfactant complexes, fac-[Re(CO)3(bpy)(L)]PF6 [bpy = 2,2′-bipyridine, L = trans-4-dodecyloxy-4′-stilbazole (L1), trans-4-octadecyloxy-4′-stilbazole (L2), 4-(4′-dodecyloxyphenylethynyl)pyridine (L3)] were synthesized and characterised. The X-ray crystal structure of fac-[Re(CO)3(bpy)(L1)]PF6 has been determined. The complexes exhibited intense photo-luminescence which has been ascribed to the dπ(Re) ⇄ π*(bpy) metal-to-ligand charge transfer (MLCT) triplet emission. The complexes were found to form stable Langmuir−Blodgett (LB) films with relatively high collapse pressures. The organic light-emitting diodes (OLEDs) fabricated by employing the LB films of various complexes as the emitting layer exhibited electroluminescence (EL) behavior. The luminances of the EL devices were found to vary as a function of the number of LB film layers, hydrocarbon chain length and the deposition types. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)