In this contribution, we have designed and synthesized a novel carbazole-1,3,4-oxadiazole based bipolar fluorophore (E)-2-(4-(4-(9H-carbazol-9-yl)styryl)phenyl)-5-(4-(tertbutyl) phenyl)-1,3,4-oxadiazole (CBZ-OXA-IV). Wittig reaction is utilised for the synthesis of the designed bipolar target compound CBZ-OXA-IV. ¹H NMR, ¹³C NMR, FT-IR and ESI–MS results confirmed the designed chemical structure of the fluorophore CBZ-OXA-IV. The photophysical properties have been investigated in detail using UV–Vis absorption, photoluminescence spectroscopy. Also, the photoluminescence studies on solid state samples (as thin films) were carried out. The CBZ-OXA-IV dye emits intense deep blue fluorescence with observed absorption and emission maxima occurring are at 353 nm and 470 nm, respectively. Fluorophore CBZ-OXA-IV has shown high Stokes shift of 7052 cm⁻¹. The experimentally measured optical band gap (\({E}_{g}^{opt}\)) value is found to be 3.01 eV and the fluorescence quantum yields (Φ_f) is 0.40. The intramolecular charge transfer property of CBZ-OXA-IV dye was examined by using photophysical properties such as absorption, emission in different solvents of different varying polarities. In addition, Density Functional Theory computations are studied in detail including the MEP surface plots and natural bond orbital analysis. The electrochemical properties have been investigated in detail by using cyclic voltammetry measurements. Thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC) measurement results display a high thermal stability with decomposition temperature (T_d5%) 387 °C and a large glass transition temperature (Tg) of 98 °C. The obtained results demonstrated that the novel bipolar fluorophore CBZ-OXA-IV could play an important role in organic optoelectronics and possibly can be utilized as bipolar transport materials for electroluminescence applications in optoelectronic devices/OLEDs.

Graphical abstract

中文翻译：

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高π-共轭双极咔唑-1,3,4-恶二唑基D-π-A型高效深蓝色荧光染料的光物理和电化学性质

在此贡献中，我们设计并合成了一种新型基于咔唑-1,3,4-恶二唑的双极荧光团 (E)-2-(4-(4-(9H-carbazol-9-yl)styryl)phenyl)-5 -(4-(叔丁基)苯基)-1,3,4-恶二唑 (CBZ-OXA-IV)。Wittig反应用于合成设计的双极性目标化合物CBZ-OXA-IV。 ¹ H NMR、¹³ C NMR、FT-IR 和 ESI-MS 结果证实了荧光团CBZ-OXA-IV的设计化学结构。已经使用紫外-可见吸收、光致发光光谱详细研究了光物理性质。此外，还对固态样品（如薄膜）进行了光致发光研究。CBZ -OXA-IV染料发出强烈的深蓝色荧光，观察到的吸收和发射最大值分别出现在 353 nm 和 470 nm 处。荧光团CBZ-OXA-IV显示出7052 cm ^-1的高斯托克斯位移。实验测量的光学带隙 ( \({E}_{g}^{opt}\) )值为3.01 eV，荧光量子产率 (Φ _f ) 为 0.40。CBZ-OXA-IV的分子内电荷转移特性通过使用光物理特性（例如在不同极性的不同溶剂中的吸收、发射）来检查染料。此外，还详细研究了密度泛函理论计算，包括 MEP 表面图和自然键轨道分析。通过使用循环伏安法测量详细研究了电化学性质。热重分析 (TGA) 和差示扫描量热法 (DSC) 测量结果显示热稳定性高，分解温度 ( T _d5% )为387 °C，玻璃化转变温度 ( T g) 高达 98 °C。获得的结果表明新型双极荧光团CBZ-OXA-IV可以在有机光电子学中发挥重要作用，并可能用作光电器件/OLED 中电致发光应用的双极传输材料。

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