【作者】 孙会彬；

【导师】 黄维； 刘淑娟；

【作者基本信息】 南京邮电大学 ， 信息材料， 2013， 博士

【摘要】 磷光金属配合物具有高的发光效率、大的Stokes位移以及发光颜色易调节等优异的光物理性质。尤其是发光性能最好的磷光铱配合物引起人们广泛的研究兴趣,并已在有机发光二极管(OLEDs)、发光电化学池(LECs)、磷光传感、生物标记和成像等领域获得了广泛的应用。然而目前的磷光金属配合物的光物理性质调控方法还主要基于对配体的化学修饰,或合成新的配体骨架,而这往往需要复杂的化学反应。随着研究的不断深入,目前所使用的构建磷光配合物的方法已经限制了其进一步发展。因此有必要提出全新的高性能磷光配合物的构建方法和光物理性能调控新策略,并以此为契机进一步拓展磷光配合物在光电子器件和生物医学领域的应用空间。这也正是本论文的主要研究内容。具体如下：1、利用抗衡离子调控铱配合物光物理性质的新策略通过选取含有氢键给体单元的N^N配体构建了一类新型的阳离子磷光铱配合物。这类配合物的特殊之处在于无论是在固态还是溶液状态下,其抗衡离子除了和阳离子中心具有静电相互作用外还和配体具有氢键相互作用,因而使通过抗衡离子调节配合物的光物理性能成为可能。我们选取了六种具有不同离子半径的阴离子作为抗衡离子,通过单晶衍射和1H NMR实验分别证明了在固态和溶液状态下这种氢键形式的存在。通过对含有不同抗衡离子的铱配合物的光物理性质的研究,我们发现通过改变抗衡离子可以有效的对配合物的发光颜色进行调节。以配合物[(ppy)2IrNH]+A为例,我们通过改变抗衡离子的类型可以对配合物的发光颜色在橙光到绿光之间进行连续性调节。最后,我们通过研究含有不同抗衡离子的铱配合物的1HNMR图谱的变化并结合理论计算结果提出了这种光物理性质调节的机理,即由于不同的抗衡离子所形成的氢键强弱不同,从而导致配体中氢键给体单元上的电子结构发生变化,进而影响到配合物发光中心的光物理性质。2、具有不同抗衡离子的铱配合物对外界刺激的响应性研究配合物[(ppy)2IrNH]+PF6在固态下表现出明显的研磨磷光变色现象。通过对配合物[(ppy)2IrNH]+PF6的晶体进行研磨可以使配合物由绿色发光变为橙色发光,这种橙色发光粉末可以在二氯甲烷的蒸汽氛围下恢复到原来的绿色发光状态。而且,通过二次研磨又可使配合物变为橙色发光状态。这个过程可以重复多次进行。通过XRD粉末衍射及红外光谱测试,我们提出这种固态下发光颜色的变化是由外界环境诱导的分子内氢键的断裂和修复引起的。另外,配合物[(ppy)2IrNH]+PF6在溶液状态下还表现出明显的电致瞵光变色现象。在外界电场存在的情况下,配合物的发光颜色会由原来的橙色发光变为绿色发光。这种在电场作用下溶液发光颜色的变化是由于电场诱使配体中氢键给体单元上的N-H键的极化引起。最后,基于配合物这种对外界刺激的特殊光物理性质响应,我们分别构建了两类信息存储器件。3、氟离子对铱配合物光物理性质的调控机理研究我们合成了三种具有不同环金属配体的以2-吡啶基苯并咪唑作为NAN配体的阳离子铱配合物(2fnpy)2IrNH]+PF6-、[(ppy)2IrNH]+PF6-和[(tpq)2IrNH]+PF6-。由于咪唑上的NH单元能与氟离子发生氢键相互作用,我们通过紫外—可见吸收光谱及光致发光光谱考察了氟离子对这三种配合物光物理性质的影响。结果发现,对于不同的环金属配体,配合物对氟离子表现出不同的光谱响应现象。当向配合物的二氯甲烷溶液加入氟离子时,蓝绿光铱配合物[(2fnpy)2IrNH]+PF6-发光强度变弱,黄橙光铱配合物[(ppy)2IrNH]+PF6-的发光颜色发生明显的蓝移,而红光铱配合物[(tpq)2IrNH]+PF6-的发光颜色却发生了红移。通过1HNMR和19F NMR,我们详细研究了氟离子与配合物之间的相互作用。结果表明,当氟离子浓度比较低时会优先与咪唑环上的NH单元形成氢键；随着氟离子浓度的进一步增加,氟离子会夺取NH上的质子,诱导配合物发生由离子型到中性的转变。通过理论计算,我们详细研究了这种离子型配合物与中性配合物的激发态性质。4、铱/硼异核配合物的光物理性质调控与细胞成像研究基于三种绿光、黄光和红光配体的铱配合物,并以多齿配体邻羟基吡啶羧酸作为桥连单元,我们成功构建了一类新型的硼杂异核铱配合物。首先,通过单晶X射线衍射实验、1HNMR、19F NMR和质谱对这类配合物的结构进行了表征；然后,通过紫外—可见吸收光谱以及荧光光谱详细研究了溶液和固态下BF2单元的引入对铱配合物光物理性质的影响。结果发现,对于不同的环金属配体,BF2单元的引入对配合物光物理性质的影响不同。相比于对应的单核铱配合物(2fppy)2Irpic]、[(ppy)2Irpic]和[(tpq)2Irpic], BF2单元引入导致配合物[(2fppy)2IrpicBF2]、[(ppy)2IrpicBF2]和[(tpq)2IrpicBF2]的发光性质分别表现为发光红移、发光变弱和发光蓝移。通过理论计算我们还详细研究了BF2单元的引入对铱配合物电子结构和激发态性质的影响。最后我们还成功的将这类配合物应用于细胞成像。5、基于聚集诱导磷光发射性质的纳米探针与细胞成像研究在本章中,我们首先合成了一类具有聚集诱导磷光发射性质的铂配合物,通过紫外—可见吸收光谱和发射光谱详细研究了这类配合物的光物理性质。基于这类材料,我们利用再沉淀法和苯乙烯微乳液聚合包覆法分别制备了具有磷光发射性质的纳米粒子。利用时间分辨光谱实验证明了这类磷光纳米材料在时间分辨成像领域的应用潜力。通过对磷光纳米粒子的表面进行生物功能化,制备了具有癌细胞靶向功能的磷光纳米探针,并成功应用于癌细胞靶向磷光成像。更多还原

【Abstract】 Phosphorescent metal complexes have been attracting wide spread interest in recent year because of the excellent photophysical properties, such as high luminescence efficiencies, significant Stokes shifts and easy-to-ajust emission properties. And all these merits make phosphorescent metal complexes been promising for various applications such as organic light emitting diodes (OLEDs), light-emitting electrochemical cells (LECs), phosphorescent sensor and bio-imaging. However, the traditional photophysical properties tuning methods are mainly based on the chemical modification of the existing ligand or construction of new ligand skeleton, which always involves the complicated chemical reaction. With the ongoing development of materials science, however, this tradition construction strategy of new metal complexes have seriously limit the further developments of metal complexes. Therefore, it is necessary to develop new construction methods and photophysical tuning strategies of metal complexes, which will offer an opportunity to further expand the application space of phosphorescent metal complexes in optoelectronics device field. In this thesis, we have carry out the research as follows.1. The new photophysical properties tuning strategy of ionic iridium complexes based on conterions2-(2-pyridyl)benzimidazole was chosen as N^N ligand to synthesise the cationic iridium complexes [(ppy)2IrNH]+A-.Through single crystal diffraction and’H NMR we have demonstrate that there exist hydrogen bonding interaction between conterions and cation centre in both solid and solution state, except for electrostatic interaction. The conterions depended photophysical properties of [(ppy)2IrNH]+A-were investigated through photoluminescence spectrum. In CH2Cl2solution, as the changes of conterions, the emission wavelength of complex [(ppy)2IrNH]+A-can be regulated continuously between490nm and584nm. By contrast with1H NMR spectra of iridium complexes with various conterions, in combination with calculated results, we conclude that the couterions depended photophysical properties is the result of electronic structure changing of hydrogen donor, which is affected by the counterions.2. The piezochromic and electrochromism of ionic iridium complex with hydrogen bond donor in the ligand, mechanism and application study.We have prepared and discovered cationic complexes [(ppy)2IrNH]+A-exhibiting a fascinating piezochromic and electrochromism phosphorescence. For piezochromic, the emission colour of complex in solid can be switched revcrsibly by grinding and vapour fuming. Based on the PXRD, CP/MAS, NMR and IR studies, we found that this piezochromic phosphorescence origin could be attributed to a hydrogen bond destruction and restoration along with amorphous-crystalline phase transformation. For electrochromism, the emission colour of complex in acetonitrile solution can be switched reversibly by adding and removing electric field. Based on the1H and19F NMR and CP/MAS, we found that this electrochromism phosphorescence origin could be attributed to the polarisation of the N-H bond of the ligand under external electric field. Finally, we have designed optical and electric recording devices based on the piezochromic and electrochromism, respectively.3. Study on the spectra response mechanism of three ionic iridium complexes with different cyclomedtalating ligand to fluoride ion, by1H NMR and theoretical calculation.We have synthesised three ionic iridium complexes with different cyclomedtalating ligand based on2-(2-pyridyl)benzimidazole as N^N ligand:[(2fnpy)2IrNH]+PF6-,[(ppy)2IrNH]+PF6-and [(tpq)2IrNH]+PF6-. The response of iridium complexes to fluoride ion were studied through the UV-vis absorption and photoluminescence spectra. As the addition of fluoride ion, the emission properties of this three iridium complexes show different changes. For [(2fnpy)2IrNH]+PF6-the emission will be quenched, and for [(ppy)2IrNH]+PF6-the emission will be blue-shift, whereas [(tpq)2IrNH]+PF6-will be red-shift. The]1H NMR changes of iridium complexes with the addition of fluoride ion shown that at the low concentration of fluoride ion it formed firstly hydrogen bond between fluoride ion and NH group, with the increase of fluoride ion concentration the NH group will be further deprotonated, in consequence, the ionic iridium complexes will be changed to neutral iridium complexes.4. Heteronuclear phosphorescent iridium(Ⅲ) complexes with tunable photophysical and excited-state properties by chelating BF2moiety for application in bioimagingIn the present study, we explored a novel design strategy of heteronuclear phosphorescent iridium(Ⅲ) complexes chelated by BF2moiety with3-hydroxypicolinic acid as the chelate ligand and synthesized a new series of iridium(Ⅲ) complexes [Ir(dfppy)2(hpa)BF2](1b),[Ir(ppy)2(hpa)BF2](2b) and [Ir(tpq)2(hpa)BF2](3b)(hpa=3-hydroxypicolinic acid, dfppy=2-(2,4-difluorophenyl)pyridine, ppy=2-phenylpyridine, tpq=2-(thiophen-2-yl)quinoline) under mild conditions. The emission colors and wavelengths of iridium(Ⅲ) complexes can be affected evidently by chelating BF2moiety into iridium(Ⅲ) complexes, and this effect will be changed with the difference of cyclometalating CAN ligands. A combination of UV-vis absorption, photoluminescence, excited-state lifetime measurements and theoretical calculations has provided the significant insight into the nature of the excited state and photophysical properties of these interesting iridium(Ⅲ) complexes. Moreover, the exclusive staining of cytoplasm and low cytotoxicity were demonstrated for these new iridium(Ⅲ) complexes, which make them promising candidates as multi-color phosphorescent dyes for living cell imaging.5. Design of nano materials with aggregation-induced phosphorescent emission and their promising applications in time-resolved luminescence assay and targeted phosphorescence imaging of cancer cellsA series of cyclometalated Pt(Ⅱ) complexes with AIPE properties have been exploited, we demonstrated their application in time-resolved luminescence assay to eliminate the interference from background fluorescence utilizing the long emission lifetime of phosphorescent signal, which is their advantage compared with fluorescent organic dyes. Moreover, the targeted phosphorescence imaging of cancer cells based on AIPE-active polymer nanoparticles have been realized.更多还原