Blue light emission from a fluorene-carbazole-fluorene trimer incorporated as the side chain into a polynorbornene

A well defined blue electroluminescent fluorene-carbazol-fluorene trimer 3,6-bis-(9,9-dihexyl-9H-fluoren-3-yl)-9-alkyl-9H-carbazole was synthesized using a Suzuki type cross coupling reaction as the key step. A way to attach this chromophore to a norbomene was developed and the resulting electroactive monomer was polymerised using the "3rd generation Grubbs catalyst" (N,N-bis(mesityl) 4,5-dihydroimidazol-2-ylidene)(3-bromo-pyridine) 2(Cl)2Ru=CHPh), yielding an amorphous polymer with a narrow molecular weight distribution, which was used to build a light-emitting diode exhibiting electroluminescence peaking at 410 nm.