设计合成了空穴传输性咔唑基团修饰的吡嗪配体,2,3-二(4-(9-咔唑基甲基)苯基)-5-甲基吡嗪(CzMPMP)及其铱配合物Ir(CzMPMP)2(acac)(acac:乙酰丙酮).用核磁共振(NMR)、质谱、元素分析等方法对其进行了表征,并用紫外-可见吸收光谱、液相和固相光致发光光谱对其光学性质进行了研究.通过与没有咔唑取代基的2,3-二苯基-5-甲基吡嗪铱配合物Ir(DPMP)2(acac)进行对照,说明咔唑基团对配合物的光学性质有显著影响.不含咔唑取代基的配合物Ir(DPMP)2(acac)的固态光致发光光谱中存在很强的激活双体(excimer)峰,而Ir(CzMPMP)2(acac)的固态光致发光光谱中未发现有激活双体峰;并且在溶液中,含有咔唑取代基的配合物Ir(CzMPMP)2(acac)较Ir(DPMP)2(acac)的光致发光强度有显著提高.这些结果说明咔唑基团的空间位阻可以有效阻止配合物成膜时产生激活双体,从而消除发射峰红移现象并提高发光效率.
We designed and synthesized a new pyrazine derivative containing the carbazyl moiety,2,3-di(4-(9carbazylmethyl)phenyl)-5-methylpyrazine(CzMPMP) and investigated its reaction with iridium(Ⅲ) ion to form the iridium complex Ir(CzMPMP)2(acac) (acac:acetyl acetone).The complex was characterized by nuclear magnetic resonance (NMR) spectroscopy,mass spectrometry (MS) and elemental analysis (EA) and its photophysical properties were investigated by UV-Vis spectroscopy as well as solution and solid state photoluminescence (PL) techniques.By comparing Ir(CzMPMP)2(acac) with Ir(DPMP)2(acac) (DPMP:2,3-diphenyl-5-methylpyrazine),we find that the carbazyl group greatly influences the photophysical properties of the complexes.Firstly,Ir(DPMP)2(acac) has a strong and broad excimer peak in its solid state PL spectrum,while Ir(CzMPMP)2(acac) has no such peak under the same conditions.Furthermore,the PL intensity of Ir(CzMPMP)2(acac) in solution increased significantly compared with Ir(DPMP)2 (acac).These results suggest that steric hindrance from the carbazyl groups may play an important role in preventing excimer formation and thus resulting in the increased PL intensity.