2-(2â²-Hydroxyphenyl)benzoxazole (HBO) and 2-(2â²-hydroxyphenyl)benzothiazole (HBT) reacted with triphenylborane produced two rigid Ï-conjugated fluorescent cores 1 (BPh2(BOZ), BOZ = 2-(benzo[d]oxazol-2-yl)phenol) and 2 (BPh2(BTZ), BTZ = 2-(benzo[d]thiazol-2-yl)phenol). Comparisons of photophysical properties and calculations between para- and meta-diphenylamine-substituted derivatives 5 (BPh2(para-NPh2-BTZ)) and 7 (BPh2(meta-NPh2-BTZ)) demonstrated that functionalization at the para-position of the rigid core is effective in tuning the electronic structure and hence the photophysical properties of this type of boron-chelate complex. Simple modification of these frameworks by introducing various amine groups at the para-position allows the synthesis of strongly fluorescent materials 3 (BPh2(para-Cz-BTZ), Cz = 9H-carbazol-9-yl), 4 (BPh2(para-NPh2-BOZ), NPh2 = diphenylamino), 5, and 6 (BPh2(para-NMe2-BTZ), NMe2 = dimethylamino). The emission colors of these newly synthesized complexes together with the parent complexes 1 and 2 covered a wide range from deep blue to saturated red in both solution and the solid state. Crystal structure analysis discloses that two phenyl groups attached to the boron atom effectively keep the luminescent ring-fused Ï-conjugated skeletons apart, making these fluorophores highly emissive in solid forms (ΦF = 0.36â0.71). Organic light-emitting diodes employing these boron complexes as emitters not only keep the full-color tunable emission feature but also show high electroluminescent (EL) performance; for instance, the greenish-blue device based on 2 showed the highest efficiency of 7.8 cd Aâ1 and the yellow light-emitting device based on 4 exhibited the highest brightness (31â220 cd mâ2) among the boron-containing emitters reported so far.
2-(2â²-羟基苯基)
苯并恶唑(HBO)和 2-(2â²-羟基苯基)
苯并噻唑(HBT)与三苯基
硼烷反应生成了两种刚性Ï-共轭荧光核心 1 (BPh2(
BOZ),
BOZ = 2-(苯并[d]
恶唑-2-基)
苯酚)和 2 (BPh2(BTZ), BTZ = 2-(苯并[d]
噻唑-2-基)
苯酚)。对位和间位
二苯胺取代衍
生物 5(BPh2(para-NPh2-BTZ))和 7(BPh2(meta-NPh2-BTZ))的光物理性质比较和计算表明,刚性核心对位的官能化可以有效地调整电子结构,从而调整这类
硼螯合物的光物理性质。通过在
硼螯合物的对位位置引入各种胺基团对这些框架进行简单的修饰,可以合成强荧光材料 3(BPh2(对位-Cz-BTZ),Cz =
9H-咔唑-9-基)、4(BPh2(对位-NPh2-
BOZ),NPh2 = 二苯基
氨基)、5 和 6(BPh2(对位-NMe2-BTZ),NMe2 = 二甲基
氨基)。这些新合成的络合物以及母体络合物 1 和 2 在溶液和固体状态下的发射颜色涵盖了从深蓝色到饱和红色的广泛范围。晶体结构分析表明,与
硼原子相连的两个苯基有效地将发光环融合的Ï-共轭骨架分开,使这些荧光团在固态下具有很高的发射率(δF = 0.36â0.71)。采用这些
硼络合物作为发射体的有机发光二极管不仅保持了全色可调发射的特点,而且显示出很高的电致发光(EL)性能;例如,基于 2 的蓝绿色器件显示出 7.8 cd Aâ1 的最高效率,而基于 4 的黄色发光器件则显示出目前所报道的含
硼发射体中最高的亮度(31â220 cd mâ2)。