Solution processable phosphorescent rhenium(i) dendrimers

Abstract

A family of (1,10-phenanthroline)rhenium(I)(CO) 3 Cl complex cored first generation dendrimers with one, two or three dendrons have been prepared. The first generation dendrons attached to the core complex are comprised of biphenyl units with 2-ethylhexyloxy surface groups at their distal ends. The number and position of attachment of the dendron to the core was found to have an effect on the properties of the dendrimers. When dendrons were attached to both the 2-and 9-positions of the 1,10-phenanthroline ligand, thus straddling the rhenium(I), the dendrimers became more electrochemically stable and less susceptible to solvatochromism. The dendrimers were generally found to have their emission blue-shifted and a higher photoluminescence quantum yield in the solid state than in the solution. The origin of this rigidochromism effect is discussed. A single layer device with a neat dendrimer film was found to have an external quantum efficiency of 0.4% (0.8 cd A 21) and power efficiency of 0.2 lm W 21 at 100 cd m 22 and 12.8 V.

Solution‐Processible Phosphorescent Blue Dendrimers Based on Biphenyl‐Dendrons and Fac‐tris(phenyltriazolyl)iridium(III) Cores

“…The final process in the formation of the monodendronized iridium(III) complexes was a triple Suzuki cross-coupling reaction of the complexes with 3,5-di[4-(2-ethylhexyloxy)phenyl]phenylboronic acid. [23] When 13 was reacted the first generation boronic acid focused dendron, dendrimer 2 was formed in an excellent 95% yield and under the same coupling conditions, 5 was isolated in a 96% yield. The synthesis of the doubly dendronized dendrimers first required the preparation of the doubly dendronized ligand.…”

Two‐Photon Absorption and Lasing in First‐Generation Bisfluorene Dendrimers

“…Synthesis: A mixture of 3,5-bis[4-(2-ethylhexyloxy)phenyl]phenylboronic acid [32] (796 mg, 1.5 mmol), 7,7 0 -dibromo-2,2 0 -bis[9,9-bis-nhexylfluorene] [33a-c] (412 mg, 0.5 mmol), tetrakis(triphenylphosphine)palladium(0) (87 mg, 0.075 mmol), toluene (1 mL), ethanol (300 mL), and 2 M NaOH (300 mL) was deoxygenated by placing under vacuum and backfilling with argon three times. The reaction was heated at reflux under argon for 24 h. After cooling, toluene (10 mL) and water (10 mL) were added, and the organic layer was separated, dried over anhydrous magnesium sulfate, filtered, and the solvent was removed.…”

Dendritic Encapsulation of Redox‐Active Units

“…158 Nonelectroactive dendrimers 159,160 and dendron-based self-assembled monolayers 161 have been explored as partial or selective blocking, surface-confined layers against redox processes by electroactive species in solution. Finally, dendrimers have become much studied electron transport and electroluminescent units in organic light emitting diodes [162][163][164][165][166][167][168][169][170][171] and solar cells. [172][173][174] In this regard, the generation of the dendrimer can be important as there is a trade-off between chromophore isolation (to prevent intramolecular luminescence quenching) and chromophore interaction (to maximize the rate of carrier transport).…”