Luminescent Nanofibers Fabricated from Phenanthroimidazole Derivatives by Organogelation: Fluorescence Response towards Acid with High Performance

Nanofibers based on phenanthroimidazole derivatives PCC , PDC , and PSC were fabricated by organogelation processes, and their fluorescence sensory properties towards acid were investigated. It was found that the emission of PCC in the nanofiber‐based film could be quenched significantly upon exposure to gaseous TFA due to the formation of protonated PCC , in which ICT (intramolecular charge transfer) would occur. On the other hand, TFA vapor led to the emitting colors of PDC and PSC in the nanofiber‐based films to turn to yellow and green from sky blue and blue, respectively. Additionally, we found that the decay times of PCC were 0.1 s and 1.9 s in probing the saturated vapor of TFA in nanofiber‐based film and in spin‐coated film, respectively. The results suggested that the high surface‐to‐volume ratio and large interspace in the nanofiber‐based networks favored the enhanced adsorption, accumulation, and diffusion of gaseous molecules, resulting in such a high performance.     

High‐Performance Blue OLEDs Based on Phenanthroimidazole Emitters via Substitutions at the C6‐ and C9‐Positions for Improving Exciton Utilization

Donor–acceptor (D–A) molecular architecture has been shown to be an effective strategy for obtaining high‐performance electroluminescent materials. In this work, two D–A molecules, Ph‐BPA‐BPI and Py‐BPA‐BPI, have been synthesized by attaching highly fluorescent phenanthrene or pyrene groups to the C6‐ and C9‐positions of a locally excited‐state emitting phenylamine–phenanthroimidazole moiety. Equipped with good physical and hybridized local and charge‐transfer properties, both molecules show high performances as blue emitters in nondoped organic light‐emitting devices (OLEDs). An OLED using Ph‐BPA‐BPI as the emitting layer exhibits deep‐blue emission with CIE coordinates of (0.15, 0.08), and a maximum external quantum efficiency (EQE), current efficiency (CE), and power efficiency (PE) of 4.56 %, 3.60 cd A^?1, and 3.66 lm W^?1, respectively. On the other hand, a Py‐BPA‐BPI‐based, sky‐blue OLED delivers the best results among nondoped OLEDs with CIE_y values of < 0.3 reported so far, for which a very low turn‐on voltage of 2.15 V, CIE coordinates of (0.17, 0.29), and maximum CE, PE, and EQE values of 10.9 cd A^?1, 10.5 lm W^?1, and 5.64 %, were achieved, respectively. More importantly, both devices show little or even no efficiency roll‐off and high singlet exciton‐utilizing efficiencies of 36.2 % for Ph‐BPA‐BPI and 39.2 % for Py‐BPA‐BPI.     

一种基于菲并咪唑的新型次氯酸荧光探针及细胞成像研究

该文设计并合成了一种基于菲并咪唑的新型次氯酸荧光探针,该探针由商用试剂9,10-菲醌和4-(甲基巯基)苯甲醛通过一步反应生成,只需简单后处理(过滤和水洗)即可得到大量纯品(产率达85%)。由于硫的重原子效应,探针荧光较弱。但在次氯酸存在下,探针分子内的硫原子被氧化成亚砜,重原子效应减弱,同时分子内电荷转移效应(ICT)加强,导致荧光增强。借助高分辨质谱,证明了探针与次氯酸盐的反应机理。在PBS缓冲溶液中(DMF∶H_2O=2∶8,体积比,pH 7.4),探针MPI可定量检测0～100μmol/L范围内的HClO,检出限为0.26μmol/L。该探针对次氯酸具有较高的灵敏性和选择性。更重要的是,MPI具有良好生物相容性和细胞渗透性,可用于活细胞内次氯酸的可视化成像。探针MPI有望为机体内次氯酸的检测与追踪提供一种可靠、有效的方法。     

Multifunctional Materials Serving as Efficient Non-Doped Violet-Blue Emitters and Host Materials for Phosphorescence

Efficient multifunctional materials acting as violet-blue emitters, as well as host materials for phosphorescent OLEDs, are crucial but rare due to demand that they should have high first singlet state (S₁) energy and first triplet state (T₁) energy simultaneously. In this study, two new violet-blue bipolar fluorophores, TPA-PI-SBF and SBF-PI-SBF , were designed and synthesized by introducing the hole transporting moiety triphenylamine (TPA) and spirobifluorene (SBF) unit that has high T₁ into high deep blue emission quantum yield group phenanthroimidazole (PI). As the results, the non-doped OLEDs based on TPA-PI-SBF exhibited excellent EL performance with a maximum external quantum efficiency (EQE_max) of 6.76 % and a violet-blue emission with Commission Internationale de L′Eclairage (CIE) of (0.152, 0.059). The device based on SBF-PI-SBF displayed EQE_max of 6.19 % with CIE of (0.159, 0.049), which nearly matches the CIE coordinates of the violet-blue emitters standard of (0.131, 0.046). These EL performances are comparable to the best reported non-doped deep or violet-blue emissive OLEDs with CIEy<0.06 in recent years. Additionally, the green, yellow and red phosphorescent OLEDs with TPA-PI-SBF and SBF-PI-SBF as host materials achieved a high EQE_max of about 20 % and low efficiency roll-off at the ultra-high luminance of 10 000 cd m⁻². These results provided a new construction strategy for designing high-performance violet-blue emitters, as well as efficient host materials for phosphorescent OLEDs.     

不对称刚性扭曲菲并咪唑分子的设计合成及其深蓝电致发光性能研究

本研究通过不对称、刚性扭曲的分子设计理念,合成了高效深蓝有机电致发光材料MBTPI。该化合物具有很高的分解温度(496℃)与玻璃转化温度(190℃),有利于提高器件的稳定性;不对称刚性扭曲的分子构型有效控制了分子的整体共轭程度,使发光波长在深蓝光区,固体发光量子产率高达74%。理论计算验证了分子不对称扭曲的构型,并且发现甲基的引入对前线轨道分布影响不大,分子保留了较好的双极性质。基于MBTPI的非掺杂器件发射出非常高效的深蓝光。色纯度为(0.15,0.07),非常接近NTSC的蓝光标准(0.14,0.08)。最大外量子效率为4.91%,并且效率滚降很小,为性能最好的非掺杂深蓝光器件之一。     

Achieving High Efficiency at High Luminance in Fluorescent Organic Light-Emitting Diodes through Triplet–Triplet Fusion Based on Phenanthroimidazole-Benzothiadiazole Derivatives

Achieving high efficiency at high luminance is one of the most important prerequisites towards practical application of any kind of light-emitting diode (LED). Herein, we report highly emissive organic fluorescent molecules based on phenanthroimidazole-benzothiadiazole derivatives capable of maintaining high external quantum efficiency (EQE) at high luminance enabled by triplet–triplet fusion (TTF) in doped organic LEDs. The PIBzP-, PIBzPCN-, and PIBzTPA-based devices showed EQEs of 8.27, 9.15, and 8.64 %, respectively, at luminance of higher than 1000 cd m⁻², with little efficiency roll-off.     

Platinum phenanthroimidazole complexes as G-quadruplex DNA selective binders

Complexes that bind and stabilize G-quadruplex DNA structures are of significant interest due to their potential to inhibit telomerase and halt tumor cell proliferation. We here report the synthesis of the first Pt(II) G-quadruplex selective molecules, containing pi-extended phenanthroimidazole ligands. Binding studies of these complexes with duplex and quadruplex d(T(4)G(4)T(4))(4) DNA were performed. Intercalation to duplex DNA was established through UV/Vis titration, CD spectroscopy, and thermal denaturation studies. Significantly stronger binding affinity of these phenanthroimidazole Pt(II) complexes to G-quadruplex DNA was observed by UV/Vis spectroscopy and competitive equilibrium dialysis studies. Observed binding constants to quadruplex DNA were nearly two orders of magnitude greater than for duplex DNA. Circular dichroism studies show that an increase in pi-surface leads to a significant increase in the thermal stability of the Pt(II)/quadruplex DNA complex. The match in the pi-surface of these phenanthroimidazole Pt(II) complexes with quadruplex DNA was further substantiated by molecular modeling studies. Numerous favorable pi-stacking interactions with the large aromatic surface of the intermolecular G-quadruplex, and unforeseen hydrogen bonds between the ancillary ethylenediamine ligands and the quadruplex phosphate backbone are predicted. Thus, both biological and computational studies suggest that coupling the square-planar geometry of Pt(II) with pi-extended ligands results in a simple and modular method to create effective G-quadruplex selective binders, which can be readily optimized for use in telomerase-based antitumor therapy.     

2-取代芳基菲并咪唑类化合物的电子结构和光谱性质的理论研究

运用密度泛函理论,在B3LYP/6-31G(d)水平上对菲并咪唑(PI)及其8种2-取代芳基衍生物的结构进行了全优化,探讨了取代基对分子结构、电离势(I_P)、电子亲和势(E_A)、电荷转移、前线分子轨道能量和电子吸收光谱等方面的影响.采用含时的度泛函理论(TD-DFT)计算了各分子的气相及液相的电子吸收光谱,计算结果与实验值十分接近.并用GaussSum2.1程序模拟吸收光谱和态密度(DOS)图,结果表明,芳基4′-位上取代基对菲并咪唑(PI)和苯环的骨架结构没有很大的扰动,但它们重新调整了菲并咪唑环和苯环中原子电荷分布,前线分子轨道(LUMO)-HOMO)能隙降低,导致8种取代的化合物的吸收波长均发生了红移.     

基于ESIPT原理的Cu^2+荧光探针

合成了一种基于激发态分子内质子转移(ESIPT)的Cu^2+荧光探针L。通过Job’s曲线、MS和1H NM R研究了探针L对Cu^2+的识别机理。与其他金属离子共存时,探针L对Cu^2+表现出良好的选择性和灵敏度。加入Cu^2+后,探针L的荧光强度逐渐降低;在365 nm紫外光的照射下,探针L溶液的颜色由蓝色变成无色。探针L具有较低的检出限(0.47μmol/L)和短的响应时间(5s)。