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研究生: 柏庫瑪
Premkumar, Gnanasekaran
論文名稱: 新型高效率雙三配位銥金屬錯合物之合成 其於有機發光二極體之應用
New Functional Bis-Tridentate Iridium (III) Phosphors and Their Application in Organic Light Emitting Diode
指導教授: 季昀
Chi, Yun
口試委員: 陳建添
Chen, Chien-Tien
蔡易州
Tsai, Yi-Chou
鄭彥如
Cheng, Yen-Ju
洪文誼
Hung, Wen-Yi
學位類別: 博士
Doctor
系所名稱: 理學院 - 化學系
Department of Chemistry
論文出版年: 2020
畢業學年度: 108
語文別: 英文
論文頁數: 227
中文關鍵詞: 磷光有機發光二極體銥金屬環金屬氮端供電子雙三配位
外文關鍵詞: Phosphorescent OLEDs, iridium, cyclometalate, N-donor, bis-tridentate
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  • 摘要
    雙三牙配位三價銥金屬錯合物的剛性結構,優異的化學和光化學穩定性在磷光OLED的生產中具有巨大的價值。然而,三牙配體的正交排列導致配體之間之相互作用,這將降低生產質量。在系列I中,為解決這一難題,開發了一系列發紅光的雙三牙銥金屬錯合物,該類錯合物所用的配合物既可以作為單陰離子輔助配位基又作為雙陰離子發光團,屬於2-pyrazolyl-6-phenyl pyridine的衍生物。通過苯基取代pyrazole N上面的H合成單陰離子螯合物(pzPhpyphH),在特定配體之特定位置引入了給電子的叔丁基/甲氧基,可微調錯合物的空間結構和電子性質。同時,pziqphH2這個負二價配位基在中央位置引入了isoquniolinyl,導致整體放光的紅移。 銥金屬(III)錯合物1.2具有出色的性能,最大效率為28.17%,41.25 cd·A-1和37.03 lm·W-1,CIEx,y = 0.63,在50 mA cm-2時為0.37,並且效率下降很小。這些觀察結果證實,大體積的叔丁基和垂直排列的苯基均有效地提高了OLED器件的性能。

    第二系列,開發了一系列均配位的雙三牙銥金屬錯合物,並從同一來源的2-pyrazolyl-6-phenyl pyridine合成,為了更好地評估分子結構和電子性能。延續第一章,單陰離子輔助配位基保持不變;而另一方面,為了提高LUMO的能級,isoqunioline體系被pyridine取代,從而引起了新系列放光的藍移。 HOMO的電子密度分布主要在pzpyph片段和中心金屬中,而LUMO的電子密度分布主要在pzPhpyph片段中。此外,structureless的放光和較大的輻射衰減速率常數表明放光主要來自MLCT和配體間電荷的轉移。

    第三章合成了一系列新的雙三牙銥金屬的磷光發光體,其同時包含雙carbene的輔助配基,例如2,6-diimidazolylidene benzene 和放光團 2-triazolyl(pyridin-3-yl)-6-phenoxy pyrimidine。在pyrimidine配體中,引入了phenoxy group以將發射光光色調節到真正的藍光區域,這取決於這些配體的能隙。pyrimidine使3MLCT的貢獻最大化,triazole增強了frontier orbitals的有效重疊。弱場的azolate被pyridin-3-yl取代,所形成的金屬-碳鍵,使被激發的以金屬為中心的dd激發態不穩定,進而提高了發射效率。
    在第IV系列中,我們在pzpyphH配合物上引入了新的取代基合成均配位雙三牙銥金屬發光體。配體的設計是通過在Ir–N配位的pyridyl片段的4號位點引入拉電子的大體積CF3取代基,並在苯基片段的第4位引入推電子的叔丁基,研究其相對應的銥金屬錯合物之光物理和改變發光性質的影響。我們合成並表徵了一系列的均配位雙三牙銥金屬錯合物。
    所有雙三牙銥金屬錯合物的結論,1H NMR光譜和參考文獻在最後呈現。


    Abstract
    The rigid structure, superior chemical, and photochemical stability of the bis-tridentate Ir(III) complexes bear tremendous value in the production of phosphorescent OLEDs. Nonetheless, tridentate chelate orthogonal arrangements result in inter-ligand interactions, which will reduce the quality of production. In series –I, to address this obstacle, a sequence of red-emitting bis-tridentate Ir(III) complexes comprising both monoanionic ancillary and dianionic chromophoric chelates are developed and synthesized as functional derivatives of 2-pyrazolyl-6-phenyl pyridine. The application of phenyl substituent to the pyrazolyl fragment of pzpyphH2 allows for the precursors of monoanionic chelates (pzPhpyphH), the insertion of electron-donating t-butyl/ methoxy groups at a particular chelate location, possibly to fine-tuning the steric and electronic properties of chelates. While dianionic chelate precursors were wisely prepared on pziqphH2 with a central isoquniolinyl system to give redshifted emissions. Ir(III) complex 1.2 gives superior performance with max. efficiencies of 28.17%, 41.25 cd·A−1 and 37.03 lm·W−1, CIEx,y = 0.63, 0.37 at 50 mA cm−2, and small efficiency roll-off. Thus, these observations confirmed a notion that the performance of OLED devices were effectively boosted by both the bulky t-butyl and perpendicular arranged phenyl groups.
    In series –II, a series of homoleptic bis-tridentate Ir(III) complexes are developed and synthesized from the same source of 2-pyrazolyl-6-phenyl pyridine in order to have a better understanding on molecular structure and electronic properties. From chapter I, monoanionic ancillary chelate remained unchanged. On the other side, to raise the LUMO energy level, the main isoquinoline system was substituted with pyridine, which gives the blue-shifted emission relative to series –I. HOMO's electron density distributions are predominantly distributed in the first pzpyph fragment and the metal atom Ir(III), while LUMO's electron density distribution is primarily located in the second pzPhpyph fragment. Additionally, structureless emission and large radiative decay rate constants manifesting that the emission has a significant contribution from MLCT and ligand-to-ligand charge transfer process.
    A new class of bis-tridentate Ir(III) metal phosphors containing both the ancillary dicarbene pincer such as 2,6-diimidazolylidene benzene and the chromophoric chelate 2-triazolyl(pyridin-3-yl)-6-phenoxy pyrimidine were synthesized in sequence –III. In pyrimidine ligands, the phenoxy group was introduced for tuning emission color into the true blue region, which is dependent on the suggested higher ligand-centered energy gap for these chelates. Pyrimidine to maximize the contribution of 3MLCT, trizolate functional groups enhance the efficient overlapping of the frontier orbitals. Soft field azolate functional group substituted by pyridin-3-yl fragment, metal-carbon bond to destabilize the excited metal-centered dd excited state and increase the efficiency of emission.
    In series – IV, we have extended the homoleptic bis-tridentate Ir(III) phosphors bearing functional derivative of a pzpyphH chelate. The ligand designed by the incorporation of electron-withdrawing, bulky trifluoromethyl substituent at the 4th position of the Ir–N coordinated pyridyl fragment and incorporation of electron-donating tert-butyl group at the 4th position of the phenyl fragment with a view to understanding the electronic effects on the photophysical and electroluminescent properties of the corresponding Ir(III) complexes. We prepared a series of homoleptic, bis-tridentate Ir(III) complexes have been synthesized and characterized.
    Lastly, the concluding remarks and 1H NMR spectrums of all bis-tridentate Ir(III) complexes and references.

    Table of Contents Abstract.................................................................................................................2 Acknowledgments.................................................................................................6 List of Figures .....................................................................................................13 List of Tables ......................................................................................................17 List of Publications..............................................................................................18 List of Abbreviations and Symbols ....................................................................19   Table of Content Chapter 1 Introduction to Organic Light-Emitting Diode (OLED) 25 1.1 Origin and Foreword 25 1.2 Recent progress and Applications of OLED 27 1.3 Principles of Photoluminescence 29 1.4 Principles of Electroluminescence 33 1.5 Introduction to phosphorescent materials 34 1.6 Introduction to multilayer Organic Light-Emitting Diodes (OLEDs) 35 1.6.1 Förster resonance energy transfer (FRET) 37 1.6.2 Dexter Energy Transfer 38 1.7. Literature review of Iridium phosphors 40 1.7.1 Introduction of phosphorescent transition metal complex 40 1.7.2. Introduction of blue phosphorescent Ir(III) complexes 43 1.7.3. Introduction of fluorine-free blue phosphorescent Ir(III) complexes 49 1.7.4. Introduction of NHC tri-bidentate Ir(III) complexes 51 1.7.5. Introduction of bis-tridentate Ir(III) complexes 54 1.7.6. Introduction of non-conjugate bis-tridentate Ir(III) complexes 61 1.7.7. Introduction of Ir(III) complexes bearing pyrimidine functionality 62 1.8. Introduction to supramolecular caged Ir(III) phosphors 65 1.9. Thesis Motivation 66 Chapter 2 Synthesis of Ligand and Complexes 69 2.1. Reagents and Instruments 69 2.1.1. Solvents and Reagents: 69 2.1.2. Analytical instruments and experimental methods 69 2.2. Structural Drawings of (N^N^C)H Series Monoanionic Ligand Precursors 74 2.2.1. General Procedure for Synthesis of Monoanionic Ligand Precursor pzPhpyphH (A1H) 74 2.2.2. General Procedure for Synthesis of Monoanionic Ligand Precursor pzPhpyBphH (A2H) 78 2.2.3. General Procedure for Synthesis of Monoanionic Ligand Precursor pzPhpyBphBH (A3H) 80 2.2.4. General Procedure for Synthesis of Monoanionic Ligand Precursor pzPhpyphO2H (A4H) 83 2.2.5. General Procedure for Synthesis of Monoanionic Ligand Precursor pzPhiqphH (A5H) 85 2.3. Structural Drawings of (N^N^C)H2 Series Dianionic Ligand Precursors 89 2.3.1. General Procedure for Synthesis of Dianionic Ligand Precursor pziqphH2 (L1H2) 89 2.3.2. General Procedure for Synthesis of Dianionic Ligand Precursor pziqphO2H2 (L2H2) 90 2.3.3. General Procedure for Synthesis of Dianionic Ligand Precursor pzpyphH2 (L3H2) 94 2.3.4. General Procedure for Synthesis of Dianionic Ligand Precursor pzpyBphBH2 (L4H2) 95 2.3.5. General Procedure for Synthesis of Dianionic Ligand Precursor pzben[h]qH2 (L5H2) 96 2.3.6. General Procedure for Synthesis of Dianionic Ligand Precursor pzpyCF3phBH2 (L6H2) 97 2.4. Structural Drawings of (C^C^C)H Series Monoanionic Ligand Precursors 99 2.4.1 General Procedure for Synthesis of Dicarbene Monoanionic Ligand Precursor mimfH (A1’H3) 100 2.4.2. General Procedure for Synthesis of Dicarbene Monoanionic Ligand Precursor mimfH (A2’H3) 103 2.5. Structural drawings of pyrimidine based (N^N^C)H2 and (C^N^C)H2 dianionic ligand precursors 104 2.5.1. General Procedure for Synthesis of Pyrimidine Dianionic Ligand Precursor tzmphH2 (L7H2) 104 2.5.2. General Procedure for Synthesis of Pyrimidine Dianionic Ligand Precursor tzmOphH2 (L8H2) 107 2.5.3. General Procedure for Synthesis of Pyrimidine Dianionic Ligand Precursor pyFmOphH2 (L9H2) 109 2.5.4. General Procedure for Synthesis of Pyrimidine Dianionic Ligand Precursor pyO2pmOphH2 (L10H2) 111 2.6. Series –I, Structural Drawings of the Studied Red Emitting Bis-Tridentate Ir(III) metal Complexes 1.1 – 1.6 114 2.6.1. General Procedure for Synthesis of Bis-Tridentate Iridium(III) Phosphors 115 2.6.2. Series –II, Structural Drawings of the Studied Green Bis-Tridentate Ir(III) metal Complexes 2.1 – 2.5 122 2.7. Series –III, Structural Drawings of the Studied Pyrimidine based Bis-Tridentate Ir(III) metal Complexes 3.1 – 3.6 127 2.7.1. General Procedure for Synthesis of Pyrimidine Chromophoric Bis-Tridentate Iridium(III) Phosphors 127 2.7.2. General Procedure for Synthesis of Pyrimidine Chromophoric Bis-Tridentate Iridium(III) Phosphors 130 2.8. Series –IV, Structural Drawings of the Studied Homoleptic Bis-Tridentate Ir(III) metal Complexes 4.1 – 4.4 133 2.8.1. Synthesis of [Ir(L6)(L6H)] (4.1) 133 2.8.2. Synthesis of [Ir(L6)(L6Me)] (4.2) 134 2.8.3. Synthesis of [Ir(L6Me)2][PF6] (4.3) 135 2.8.4. Synthesis of [Ir(L6)2][NBu4] (4.4) 136 Chapter 3 Results and discussion 138 3.1. Series –I, Structural Drawings of the Studied Red Emitting Bis-Tridentate Ir(III) metal Complexes 1.1 – 1.6 138 3.1.1. Introduction to Molecular Design 138 3.1.2. X-ray Crystallography 140 3.1.3. Photophysical Properties 144 3.1.4. Electrochemical Properties 146 3.1.5. Theoretical investigation 148 3.1.6. Thermal Analysis 154 3.1.7. OLED Fabrication and Characterization 155 3.1.8. Concluding Remarks 158 3.2. Series –II, Structural Drawings of the Studied Homelptic Bis-Tridentate Ir(III) metal Complexes 2.1 – 2.5 160 3.2.1. Introduction to Molecular Design 160 3.2.2. X-ray Crystallography 162 3.2.3. Photophysical Properties 166 3.2.4. Electrochemical Properties 168 3.2.5. Thermal Analysis 170 3.2.6. Concluding Remarks 171 3.3. Series –III, Structural Drawings of the Studied Pyrimidine based Bis-Tridentate Ir(III) metal Complexes 3.1 – 3.6 173 3.3.1. Introduction to Molecular Design 173 3.3.2. X-ray Crystallography 177 3.3.3. Photophysical Properties 181 3.3.4. Electrochemical Properties 183 3.3.5. Concluding Remarks 185 3.4. Series –IV, Structural Drawings of the Studied Homoleptic Bis-Tridentate Ir(III) metal Complexes 4.1 – 4.4 187 3.4.1. Introduction to Molecular Design 187 3.4.2. Photophysical Properties 188 3.4.3. Electrochemical Properties 191 3.4.4. Concluding Remarks 192 Chapter 4 Conclusion. 193 4.1. NMR Spectrum of Complexes 195 4.3. References 216   List of Figures Chapter-1 Figure 1.1. Smartphone with OLED screens. 27 Figure 1.2. a) Samsung first foldable smartphone with OLED screens, b) LG rollable OLED TV. 28 Figure 1.3. Samsung transparent OLED screens. 29 Figure 1.4. Jablonski diagram. 31 Figure 1.5. Oxygen quenching mechanism of phosphorescence. 32 Figure 1.6. Electroluminescent process. 33 Figure 1.7. OLED device structure. 36 Figure 1.8. Förster energy transfer mechanism. 37 Figure 1.9. Dexter electron transfer mechanism. 38 Figure 1.10. The emission pathway of electrically generated excitons in OLEDs. 39 Figure 1.11. Structural drawing of PtOEP (left), External quantum efficiency (middle) and Emission spectrum with device architecture (right). 41 Figure 1.12. External quantum efficiency with CBP as the dopant in OLED device architecture. 41 Figure 1.13. Device architecture (left), External quantum efficiency (middle) and Emission spectrum with CIE coordinates of Ir(ppy)3 in CBP (right). 42 Figure 1.14. Series of homoleptic cyclometalated iridium(III) complexes. 43 Figure 1.15. Universal Display Corporation’s PhOLED material performance at SID-2011. 44 Figure 1.16. Structural drawings of FIrpic, Ir(Fppy)2(acaa) and Ir(ppy)2(acaa), its emission spectrum (left), electroluminescent spectra of FIrpic elements (top right), the external quantum efficiency of FIrpic device and triplet state energy transfer mechanism (bottom right). 45 Figure 1.17. Phosphorescence spectra and chemical structure of FIrpic, mCP, and CBP (left), Molecular structure and FIrpic and CDBP and EL spectrum of an OLEDs and energy level diagram (right). 46 Figure 1.18. Structural drawing of TCTA and B3PyPB. 46 Figure 1.19. Structural drawing of iridium complexes bearing pyrazolyl borate chelate and Emission spectrum of iridium complexes at RT. 47 Figure 1.20. Structural drawing of iridium FIrpic, FIrtaz and FIrN4 complexes and host materials (left), the Emission spectrum of Blue phosphorescent emitters (middle) and Photoluminescence in DCM solution (right). 48 Figure 1.21. Structural drawing of iridium complexes 1 and 2 (left), Absorption and emission spectrum of blue phosphorescent emitters (right). 49 Figure 1.22. EL characteristic of complex 1: Current-voltage- luminescence characteristics and EL inset (left), external quantum and power efficiency (middle), comparison of CIE coordinates of the several blue phosphorescent dopants (right). 49 Figure 1.23. Structural drawings of Ir(III) complexes 1-4 bearing pyrimidine bidentate chelate and absorption and emission spectrum. 50 Figure 1.24. Structural drawings of Ir(III) complexes 1-4 bearing methoxy 3-pyridyl or (3-pyrimidine) pyridine chelate and absorption and emission spectrum. 51 Figure 1.25. Structural drawings of Ir(pmb)3 and Ir(pmi)3 complexes. 52 Figure 1.26. Absorption and emission spectrum (b) Energy level diagram for fac-Ir(ppz)3 and fac-Ir(C^C:)3 compounds. 52 Figure 1.27. Structural drawings of 1 – 3 and its photophysical data. 53 Figure 1.28. (a) Structural drawings of fac-Ir(pmp)3 and mer-Ir(pmp)3 (b) Emission spectrum at 295K and 77K. (c, d) The OLED device structure of fac-Ir(pmp)3 and mer-Ir(pmp)3, respectively. 54 Figure 1.29. Structural drawings of Ir(III) complexes and (I) tridentate and (II) bidentate chelating mode of a tridentate ligand. 55 Figure 1.30. Structures of the Iridium Complexes Isolated, Containing the N^C^N-Bound Ligand dpyx, Obtained through the Intermediacy of [Ir(dpyx)Cl(í-Cl)]2 (1). 56 Figure 1.31. Structural drawing of bis-tridentate Ir(III) complexes 1-6 bearing (N^C^N) and (C^N^N) and its absorption and emission spectrum. 57 Figure 1.32. Structural drawings of Ir(III) complexes (1-6) bearing (C^N^C) ancillary chelate and UV/Vis absorption and emission spectrum of Ir(III) complexes (1-5). 58 Figure 1.33. (a) Structural drawings of (C^C^C) tridentate chelates. (b) Structural drawing of bis-tridentate Ir(III) complexes. (c) UV/Vis absorption and emission spectrum. (d) External quantum and power efficiency. 59 Figure 1.34. Schematic diagram showing the dual coordinating mode of (C^N^N). 60 Figure 1.35. Structural drawings of homoleptic bis-tridentate Ir(III) complexes (top left), UV/Vis absorption and emission spectrum (top right), and photophysical properties. 61 Figure 1.36. (a) Structural drawings of the sky-blue emitter and tridentate chelates. (b) Structural drawing of bis-tridentate Ir(III) complexes. (c) Emission spectrum. (d) External quantum and power efficiency. 62 Figure 1.37 Structure for the complexes FIrpic, MS2, MS17, and MS19. 63 Figure 1.38. (a) Absorption and emission spectrum, (b) Photoluminescence in solution, (c) Transient PL decay curves of FIrpic, MS2, MS17, and MS19. 63 Figure 1.39. (a) Structural drawings of bis-tridentate Ir(III) complexes bearing pyrimidine functionality, (b) The emission spectrum of two isomers of pyrimidine functionality, (c) Absorption and Emission spectrum, (d) Photophysical properties. 64 Figure 1.40, (a) Structural drawing of [Ir(ppy)2(pen)][PF6] complex. (b) Structural drawing of [Ir(4Fppy)2(pbpy)] [PF6]. Both complexes showing face-to-face π-π stacking interaction. 65 Chapter-3 Figure 3.1. Structural drawing of 1.1. 141 Figure 3.2. Absorption and emission spectra of Ir(III) complexes 1.1 - 1.6 recorded in CH2Cl2 at RT. 145 Figure 3.3. Cyclic voltammograms of complexes 1.1 – 1.6 measured in CH2Cl2 for an anodic sweep and in THF for a cathodic sweep. 148 Figure 3.4. Key molecular orbitals calculated based on the optimized ground-state geometry (energy level and contribution from Ir atom for electron distribution are given in the parenthesis), at PBE1PBE/6-31G**(LANL2DZ with ECP for Ir) level with PCM for modeling the CH2Cl2 solvent. 153 Figure 3.5. Frontier molecular orbitals calculated based on the geometry optimized for S0, at PBE1PBE/6-31G**(LANL2DZ with ECP for Ir) level with PCM for modeling the CH2Cl2 solvent. 154 Figure 3.6. TGA curves of complexes 1.1 – 1.6. 155 Figure 3.7. a) Schematic device configuration, energy level diagram and chemical structures of the employed materials for the OLEDs based on complexes 1.2 and 1.5 as emitters. b) Current density-voltage-luminance (J-V-L) characteristics,c) current efficiency and power efficiency versus luminance characteristics and d) external quantum efficiency versus luminance correlations of the devices (insert: EL spectra at 50 mA cm-2). 157 Figure 3.8. Structural drawing of 2.1. 163 Figure 3.9 Absorption and emission spectra of Ir(III) complexes 2.1 - 2.5 recorded in CH2Cl2 at RT. 167 Figure 3.10. Cyclic voltammograms of complexes 2.1 – 2.5 measured in CH2Cl2 for an anodic sweep and in THF for a cathodic sweep. 169 Figure 3.11. TGA curves of complexes 2.1 – 2.5. 171 Figure 3.12. a) Calculated π-elelctron density distributions for pyridine and pyrimidine, b) Partial charges on pyridine and pyrimidine. 175 Figure 3.13. Structural drawing of 3.6. 178 Figure 3.14. Partial charges on pyridine and pyrimidine based – F a and – OMe substituents. 182 Figure 3.15. Absorption and emission spectra of Ir(III) complexes 3.1 – 3.6 recorded in CH2Cl2 at RT. 182 Figure 3.16. Cyclic voltammograms of complexes 3.1 – 3.6 measured in CH2Cl2 for an anodic sweep and in THF for a cathodic sweep. 184 Figure 3.17. Absorption and emission spectra of Ir(III) complexes 4.1 – 4.4 recorded in CH2Cl2 at RT. 190 Figure 3.18. Cyclic voltammograms of complexes 4.1 – 4.4 measured in CH2Cl2 for an anodic sweep and in THF for a cathodic sweep. 191   List of Tables Table 3.1. Selected bond lengths [Å ] for complex 1.1. 141 Table 3.2. Selected bond angles [°] for complex 1.1. 142 Table 3.3. Crystal data and structure refinement for 1.1. 142 Table 3.4. Absorption and emission properties of Ir(III) metal complexes 1.1 – 1.6 recorded in CH2Cl2 at RT. 146 Table 3.5. Electrochemical and energy gap data of studied Ir(III) complexes 1.1 – 1.6. 148 Table 3.6. The calculated excitation energy (λ), oscillator strength (f), main orbital contribution and charge characters of the lowest singlet and triplet excited state for the optimized ground-state geometries of Ir(III) complexes 1.1, 1.3 and 1.4, at PBE1PBE/6-31G**(LANL2DZ with ECP for Ir) level with PCM for modeling the CH2Cl2 solvent.a) 151 Table 3.7. The calculated excitation energy (λ), oscillator strength (f), orbital contribution (>=4%) and main charge characters of the lowest singlet and triplet excited state for the optimized ground state geometries of Ir(III) complexes 1.1, 1.3 and 1.4, at PBE1PBE/6 31G**(LANL2DZ with ECP for Ir) level with PCM for modeling the CH2Cl2 solvent. 152 Table 3.8. EL performance of the OLEDs based on complexes 1.2 and 1.5. 158 Table 3.9. Selected bond lengths [Å] for complex 2.1. 163 Table 3.10. Selected bond angles [°] for complex 2.1. 164 Table 3.11. Crystal data and structure refinement for 2.1. 164 Table 3.12 Absorption and emission properties of Ir(III) metal complexes 2.1 – 2.5 recorded in CH2Cl2 at RT. 168 Table 3.13 Electrochemical and energy gap data of studied Ir(III) complexes 2.1 – 2.5. 170 Table 3.14. Selected bond lengths [Å] for complex 3.6. 178 Table 3.15. Selected bond angles [°] for complex 3.6. 179 Table 3.16. Crystal data and structure refinement for 3.6. 179 Table 3.17. Absorption and emission properties of Ir(III) metal complexes 3.1 – 3.6 recorded in CH2Cl2 at RT. 183 Table 3.18 Electrochemical and energy gap data of studied Ir(III) complexes 3.1 – 3.6. 185 Table 3.19. Absorption and emission properties of Ir(III) metal complexes 4.1 – 4.4 recorded in CH2Cl2 at RT. 190 Table 3.20 Electrochemical and energy gap data of studied Ir(III) complexes 4.1 – 4.4. 192

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