光功能铱配合物的分子设计、合成及其光电性质研究

【作者】 赵强；

【导师】 李富友； 黄春辉；

【作者基本信息】 复旦大学 ， 无机化学， 2007， 博士

【摘要】 铱配合物具有发光效率高、发光颜色可以通过改变配体结构进行调节及磷光寿命较短等优点而成为研究的热点。本论文合成了七个系列新型铱配合物（结构见附表）。首先从构效关系研究出发，详细探讨了配体化学结构与配合物光物理及电化学性质之间的关系。其次将合成的铱配合物应用于电致发光器件中，制备了高效的、具有饱和红光发射的聚合物电致发光器件。最后，研究了这类材料在化学传感器领域的应用，开发了新型基于铱配合物的磷光化学传感器。具体来说，本论文的研究内容包括以下六部分：1含有不同β-二酮配体的喹啉基铱配合物的设计、合成和光电性能研究设计、合成了一系列基于不同喹啉衍生物配体（C^N）和不同β-二酮配体（O^O）的红光铱配合物Ir（C^N）₂（O^O）。两种β-二酮配体分别是乙酰丙酮（acac）和1-苯基-3-甲基-4-（异丙基）-5-吡唑啉酮（PMIP）。通过改变喹啉衍生物配体（C^N配体）的化学结构，配合物的发射颜色可以从橙红光（596 nm）调节到饱和红光（630nm）。对于相同喹啉类配体的铱配合物而言，用PMIP作为β—二酮配体取代acac后可以明显提高配合物的发光效率。我们将其中三个配合物制备了聚合物电致发光器件，详细研究了这一系列配合物的电致发光性质，得到了具有饱和红光发射（色坐标x=0.66，y=0.34）的高效聚合物电致发光器件，最大外效率为9.6％。2含有不同辅助配体的中性铱配合物的设计、合成及聚集态引起的磷光发射（AIPE）研究我们合成了一系列含有不同三重态能级β-二酮配体（O^O）的铱配合物Ir（ppy）₂（O^O），其中ppy为2-苯基吡啶配体。在溶液中，当β-二酮配体具有高的三重态能级时，配合物具有强的磷光发射。而当β-二酮配体的三重态能级低于³ML_ppyCT时，导致非辐射跃迁。有趣的是，在固态下，溶液中不发光的配合物表现有较强的发射。我们对这种溶液和固态下的不同的发射性质进行了详细的讨论。发现不同配合物分子的ppy配体之间的强的π-π相互作用是引起聚集态发射的根本原因。并通过实验方法和理论计算对这种有趣的聚集引起的磷光发射现象进行了详细的研究，提出了新的发光机理。我们认为，由于ppy配体间强的π-π相互作用的存在，会导致π-π堆积的ppy配体能级降低，从而使聚集态下金属铱中心向π-π堆积的ppy配体之间的电荷转移跃迁（³ML_πCT）开始参与激发态，从而导致发射的产生。为了进一步利用这种分子聚集引起的磷光发射性质，我们将配合物Ir（ppy）₂（DBM）制备成了非掺杂电致发光器件。初步研究结果表明，这一类材料能够作为新的固态电致发光材料。3含N^N配体新型阳离子型铱配合物的设计、合成及发光性能研究我们选择1-苯基异喹啉（piq）作为C^N配体，设计和合成了一系列含有不同共轭长度N^N配体的离子型铱配合物[Ir（piq）₂（N^N）]⁺PF₆^-。通过理论计算、光物理和电化学性质的详细研究，我们证明配合物的激发态非常复杂，同时含有³MLCT、³LLCT和³LC(π_C^N→π_C^N^*)三种跃迁。重要的是，这种复杂的激发态可以通过改变N^N配体的共轭长度进行调节。另外，N^N配体的共轭长度的改变可以将这些配合物的发射波长从586nm调节到732nm。另外，我们在前面工作的基础上，将C^N配体piq改为2，4-二氟苯基吡啶（F₂ppy），合成了一系列新型阳离子型铱配合物[Ir（F₂ppy）₂（N^N）]⁺PF₆^-。通过简单的改变N^N配体的化学结构，实现了发光颜色从蓝光（457nm）到红光（590nm）的显著调节。4基于铱配合物的光电多信号输出的Hg²⁺化学传感器的研究利用Hg²⁺的亲硫性，研究了一种基于铱配合物Ir（btp）₂（acac）的具有高选择性和多信号输出的汞离子磷光化学传感器。可以通过紫外吸收光谱、磷光光谱和电化学方法来实现对Hg²⁺的多信号检测。Hg²⁺的加入可以导致配合物Ir（btp）₂（acac）的紫外可见吸收和发射光谱发生明显蓝移，实现了肉眼识别。5含邻菲罗啉衍生物的阳离子型铱配合物的设计、合成及其阴离子识别性能的研究我们设计、合成了一系列含有不同邻菲罗啉衍生物配体的新型离子型铱配合物，详细研究了所合成的配合物的电化学、紫外-可见吸收、磷光发光性质，并结合理论计算对配合物的激发态进行了讨论。另外阴离子和质子的加入对配合物的光物理和电化学性质的影响也进行了详细的讨论。加入CF₃COOH后，配合物的发射波长发生明显的红移，发射颜色由黄色变为深红色。F^-和CH₃COO^-的加入能够引起紫外—可见吸收和磷光发射光谱明显的变化。配合物2～4的溶液的颜色从黄绿色变为棕黄色，实现了肉眼识别。同时，F^-和CH₃COO^-的加入也淬灭了配合物的发射。尤其是，配合物2对F^-具有更强的结合能力，表明配合物2是一个有潜力的F^-磷光化学传感器。6含有机硼单元的铱配合物的合成及其氟离子识别性能研究本部分利用三价有机硼化合物是本征的强Lewis酸，与典型Lewis碱氟离子发生强相互作用的特点，合成了含有米基硼的喹林衍生物配体及基于这个配体的两个铱配合物。详细研究了它们的光物理和电化学性质。并发现，所合成的配体和配合物对F^-具有强的结合能力和高的选择性。更多还原

【Abstract】 Recently, iridium（Ⅲ） complexes have received considerable attention due to theirhigh emission efficiencies and easy tuning of emission colors by changing chemicalstructures of ligands. In this thesis, seven series of novel iridium（Ⅲ） complexes weresynthesized （Please see the table attached for the molecular structures）. Firstly, theinfluences of chemical structures of ligands on the photophysical and electrochemicalproperties of complexes were investigated in detail. Secondly, efficientelectrophosphorescent polymer-based light-emitting diodes （PLEDs） were fabricatedby doping the iridium（Ⅲ） complexes into the polymer host. Finally, the application ofiridium（Ⅲ） complexes in the field of chemical sensors has been developed.This thesis can be divided into six parts.1. Design, synthesis and optoelectronic properties of a series of iridium（Ⅲ）complexes based on quinoline derivatives and differentβ-diketonate ligands.A series of cyclometalated iridium（Ⅲ） complexes Ir（C^N）₂（O^O） based onquinoline derivatives （C^N） and differentβ-diketonate ligands （O^O） weresynthesized, where O^O denotes acetylacetonate （acac） and1-phenyl-2-methyl-4-isobutyryl-5-pyrazolonate （PMIP）. By modifying the chemicalstructures of quinoline derivative ligands, the emissive wavelengths of complexes canbe tuned from 596 to 634 nm. Interestingly, the photoluminescence quantumefficiency can be improved by the replacement of acac with PMIP. Moreover, threeiridium complexes were used as dopants to fabricated electrophosphorescentpolymer-based light-emitting.diodes （PLEDs）. The PLEDs show red emission withhigh external quantum efficiencies, ranging from 7.0 to 9.6%.2. Design, synthesis and aggregation-induced phosphorescent emission （AIPE）of a series of iridium（Ⅲ） complexes containing different ancillary ligands.We have synthesized a series of iridium（Ⅲ） complexes Ir（ppy）₂（O^O） containingβ-diketonate ligands （O^O） with different triplet energy levels, where ppy denotes2-phenyl-pyridine. In solution, complexes containingβ-diketonate ligands with hightriplet energy levels exhibit strong phosphorescent emission. When the triplet energylevels ofβ-diketonate ligands were lower than the energy level of ³ML_ppyCT, noemission was observed for complexes. Interestingly, in solid state moderately strongemission could be observed for those complexes without emission in solution. Weinvestigated the different emission properties of complexes between in solution and in solid state and found that the strongπ-πinteraction between the adjacent pyridyl ringsof ppy ligands is essential in the aggregation-induced phosphorescent emission. Westudied the interesting AIPE by experimental methods and theoretical calculation, andprovided new emission mechanism. We think that the strongπ-πinteraction betweenthe adjacent pyridyl rings of ppy ligands elongates the overallπ-conjugation degreeand reduces the energy levels ofπ_ppy^* compared with that in solution. As a result, thetriplet energy level of charge transfer state from iridium to the interacting ppy（donated as ³ML_πCT） is reduced and the ppy ligands participate in the excited state insolid state. And emission could be observed.3. Design, synthesis and emission properties of novel cationic iridium（Ⅲ）complexes with different N^N ligands.A series of new cationic iridium（Ⅲ） complexes [Ir（piq）₂（N^N）]⁺PF₆^- （1-6） （piq=1-phenyl-isoquinoline） containing N^N ligands with different conjugated lengthwere synthesized. UV-vis, photoluminescence, cyclic voltammetry and theoreticalcalculation were employed for studying the photophysical and electrochemicalproperties. And the excited state properties were investigated in detail. The excitedstate of complexes is complicated and contains triplet metal-to-ligand charge transfer（³MLCT）, triplet ligand-to-ligand charge transfer （³LLCT） and ligand centred（cyclometalated） （³LC） transitions simultaneously. In addition, the emissionwavelength can be tuned significantly from 586 to 732 nm by changing theconjugated length of N^N ligands.In addition, we replaced piq with another kind of C^N ligand2,4-difluorophenyl-pyridine （F₂ppy） and synthesized a series of new cationiciridium（Ⅲ） complexes [Ir（F₂ppy）₂（N^N）]⁺PF₆^-. By changing the N^N ligands simply,the emission colors of complexes can be tuned from blue （457 nm） to red （590 nm）.4. A highly selective and muitisignaling optical-electrochemical sensor for Hg²⁺based on phoephorescent iridium（Ⅲ） complex.Because Hg²⁺ can easily combine with sulfur, a highly selective phosphorescentchemosensor for Hg²⁺ based on iridium （Ⅲ） complex Ir（btp）₂（acac） was realized.Multisignaling changes were observed through UV-vis absorption, phosphorescentemission and electrochemical measurements. Upon addition of Hg²⁺, the obviousspectral blue-shifts in absorption and phosphorescent emission bands were measuredfor Ir（btp）₂（acac）, which could be observed by the naked eyes.5. Design and synthesis of cationic iridium（Ⅲ） complexes based on phenanthroline derivatives and their applications in chemical sensor for anions.A series of new cationic iridium （Ⅲ） complexes containing different phenanthrolinederivatives were synthesized. Their photophysical and electrochemical propertieswere investigated. The influences of anions and proton on the photophysical andelectrochemical properties were also studied in detail. After the addition of CF₃COOH,the emission wavelengths were red-shifted evidently and the emission colors werechanged from yellow to deep red. In addition, the addition of F^-, CH₃COO^- can alsocause significant variations of UV-Vis absorption and emission spectra. The solutioncolors of complex 2, 3 and 4 were changed from yellow-green to brown, which can beobserved by the naked eye. The emission of complexes was quenched completely bythe addition of F^- and CH₃COO^-. Especially, complex 2 prefers to bind F^- over theother anions, suggesting that complex 2 can be acted as a good phosphorescentchemosensor for F^-.6. Highly selective phosphorescent chemosensor for fluoride ions based onnovel iridium（Ⅲ） complexes containing aryiboranes.As the strong Lewis acid, boron atom exhibits the strong affinity toward fluride ionaccording to specific Lewis acid-base interaction. Herein, we synthesized quinolinederivative ligand containing arylboranes and two iridium（Ⅲ） complexes based on thisligand and studied their photophysical and electrochemical properties. In addition, thequinoline derivative ligand and iridium（Ⅲ） complexes can act as the highly selectivechemosensors for F^-.更多还原