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
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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 H2 O 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 H2 O and the solids obtained were filtered, washed thoroughly with H2 O and dried. Yield: 98%. The product(2d ) obtained was used in the next step without any further purification.
