Highly Fluorescent Blue-Emitting Materials from the Heck Reaction of Triphenylvinylsilane with Conjugated Dibromoaromatics

Abstract

A new family of conjugated, highly photoluminescent blue-emitting organosilicon materials prepared from the Heck reaction of triphenylvinylsilane with various dibromoaromatics is described. The products are prepared in one high-yielding step (60-79%) from readily available starting materials. Their high photoluminescent quantum yields (67-98%) coupled with moderate glass transition temperatures (Tg, 69-138 °C) make them excellent candidates for active materials in organic light-emitting diodes (OLEDs).

Key words

Heck reaction - organosilicon - photoluminescent - OLEDs - vinyl silanes

References and Notes

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19

The space-filling model was generated using Materials Studio software package from Accelrys Inc. using a molecular mechanics (MM) method.

21

A flame-dried flask was charged with t-BuONa (5.8 g, 60 mmol) and dried at 110 °C under vacuum for 1 h. After cooling to r.t., 4,4′-dibromobiphenyl (3.12 g, 10 mmol), aniline (1.83 mL, 20 mmol) and Pd[P(t-Bu)₃]₂ (25.5 mg, 5·10^-2 mmol) were added followed by 40 mL of toluene. The reaction mixture was purged using argon for a few minutes and then heated to 70 °C under an atmosphere of argon until all the amine was consumed as monitored by TLC. The reaction mixture was then cooled to r.t. followed by the addition of 4-bromo-tert-butylbenzene (3.47 mL, 20 mmol), Pd[P(t-Bu)₃]₂ (25 mg, 5·10^-2 mmol) and toluene (20 mL). The reaction mixture was then stirred at 90 °C for 15 h. Finally the reaction mixture was cooled, extracted with H₂O and the organic layer dried with MgSO₄ and concentrated to get an oily residue which was then suspended in MeOH to get a grey solid which was filtered and dried. The crude product was used as such for the next step. To a solution of the compound above (4.9 g, 8.33 mmol) in 300 mL DMF was added dropwise at r.t. a solution of N-bromosuccinimide in 100 mL DMF. After addition the reaction mixture was stirred at r.t. overnight. The reaction mixture was precipitated by pouring into acidified H₂O and the solids obtained were filtered, washed thoroughly with H₂O and dried. Yield: 98%. The product(2d) obtained was used in the next step without any further purification.