Abstract
Abstract : Hydrosilayltion of alkenes and alkynes is often catalyzed by late transition-metal complexes. 7-Oxabenzonorbornadiene and hydrosilanes HSiR3 (R = Et, (n-hexyl) and Ph) in the presence of palladium complexes, Pd(dba)2 (2.5 mol%), undergoes both ring opening hydrosilylation and b-silylation reaction. The silyl groups would add onto different position of 7-oxabenzonorbornadiene (1) depending on the substitutions of the silyl group. When the substitutions are alkyl, 1 inserts into Pd-C bond and the silyl group adds to b-carbon on the naphthyl ring. For R = Ph, 1 inserts into Pd-H bond and the silyl group adds to oxygen atom of 1. Palladium complexes, Pd(dba)2 also catalyzes the reductive dimerizatoin of 7-oxabenzonorbornadiene by HSiCl3 and HSiCl2Me at room temperature rapidly to yield 9-(2-naphthyl)-11-oxatricyclo[6.2.1.02,7] undeca-2(7),3,5-triene (11a) in good yield. 11a readily undergoes dehydration in the presence of HSiCl3 to form 2,2’-binaphthyl, 11b. The mechanism for the reductive dimerizatoin of 1 and binaphthyl formation is proposed via a 5-membered palladocycle intermediate, following by a s-bond metathesis with HSiCl3 and subsequent rearrangement to give product 11a. Furthermore, treatment of various 1,4-epoxy-1,4-dihydroarenes with HSiCl3 in toluene in the presence of a palladium complex affords the corresponding biaryls in good to excellent yields. The process appears to occur via a novel palladium-catalyzed hydrosilylative dimerization of 1,4-epoxy-1,4-dihydroarenes and subsequent elimination of HOSiCl3 and H2O. Bistriphenylene, BTP (16a) which was synthesized from the dimerization of 1,4-epoxy-1,4-dihydroarenes was used as an emitting material in an OLED (qrganic light-emitting-diode)device. Electron transporting materials is Alq（tris(8-hydroxyquinolato) aluminum） or TPBI (2,2’,2”-(1, 3, 5-benzenetriyl)tris-[1-phenyl-1H- benzimidazole]). Hole transporting materials is NPB (4,4’-bis[N-(1-naphthyl-1-)-N- phenyl-amino]-biphenyl), TPD (1,4-bis [(phenyl-m-tolyl)amino]biphenyl) or CBP (4,4’-dicarbazolyl-1,1’- biphenyl). With a device structure of [ITO/ CuPc/ NPB/ BTP/ Alq/ Mg:Ag], bright blue emission with a luminance ranging between 11000 and 16600 was observed under electric bias. The external quantum efficiency is up to 2.0% and the best current efficiency is 5.1 cd/A. However, with a device structure of [ITO/ CuPc/ NPB/ BTP/ TPBI/ Mg:Ag], the external quantum efficiency is up to 3.3% and the best current efficiency can achieve 3.3 cd/A. The turn-on voltage is between 3.5-4.5 V. The luminance is 17948 cd/m2 at 20 V and this device has an excellent CIE (x, y) value of (0.15, 0.08).