新型含吡咯亚胺基辅助配体的金属铱（Ⅲ）配合物的合成、表征及发光性质

合成了一系列含有吡咯亚胺基为辅助配体的2-苯基吡啶铱配合物[(ppy)zIr(NAN)](ppy=2-苯基吡啶),通过1H NMR,MS,HRMS和元素分析对配合物结构进行了表征,并研究了合成配合物的反应条件、紫外吸收光谱、光致发光光谱及铱配合物荧光量子产率.结果表明,在无水乙酸钠、二氯甲烷溶液中,室温反应12 h可获得较高的产率.通过改变吡咯亚胺类配体中的取代基,该类配合物在507～606 nm之间具有不同的发光波长,实现了从绿光到红光的转变.所有的铱配合物在二氯甲烷溶液(空气中)表现出较高的量子效率(0.25～0.95).     

含三芳胺基的吡啶甲酸衍生物及其环金属铱配合物的合成与性能

通过Ullmann反应和Negishi偶联反应, 合成了一种含三芳胺功能基的吡啶-2-甲酸衍生物; 并以此为辅助配体、1-苯基异喹啉为环金属配体, 设计合成了一种新型环金属铱配合物. 该配合物的二氯甲烷溶液, 在391～461 nm范围呈现了强烈的金属-配体电荷转移(MLCT)电子跃迁吸收带; 其最大发光波长为609 nm. 与传统的二(1-苯基异喹啉)(吡啶-2-甲酸)合铱配合物相比, 设计的环金属铱配合物具有增强的MLCT电子跃迁吸收和低的氧化电位, 是一种有发展潜力的红色磷光材料.     

2, 2′-联吡啶-3, 3′二羧酸铱配合物的合成、晶体结构和发光性质研究

利用环金属配体2-苯基吡啶(ppy)和辅助配体2,2'-联吡啶-3,3’-二羧酸(H2dcbpy)合成了一个铱配合物[Ir(ppy)2(Hdcbpy)],并且测定了其晶体结构。通过对配合物的紫外可见吸收光谱和发光光谱的研究表明,其常温发射位于620nm处,初步推测该磷光发射可能来自由金属到环金属配体和辅助配体的电荷转移(MLCT)跃迁。     

利用吡啶衍生物主配体共轭效应调控铱配合物发光颜色(英文)

利用2-苯基吡啶及其衍生物为主配体、四苯基膦酰亚胺为辅助配体合成了3个铱配合物Ir(ppy)2tpip(Hppy:2-苯基吡啶,Htpip:四苯基膦酰亚胺)、Ir(npy)2tpip(Hnpy:2-(1-萘基)吡啶)和Ir(pnpy)2tpip(Hpnpy:2-(9-菲基)吡啶)。它们的结构通过1H NMR和MALDI-TOF质谱进行了表征,其中配合物Ir(ppy)2tpip还进一步通过晶体结构分析验证。主配体从苯环到萘环和菲环的改变增加了配合物的π共轭,减小了能级差,导致了3种配合物的磷光发射光谱从516 nm红移到600和633 nm(从绿光到红光),发光量子效率也从0.36增加到0.51和0.53。从量化计算的结果可以看出,这种共轭效应增加了主配体的电子密度,提高了配合物的LUMO能级。配合物结构和发射性质之间的关系规律为设计不同发光颜色的铱配合物提供了思路。     

[Ir(ppy)_2(Hdcbpy)]配合物的合成、晶体结构和发光性质研究

利用环金属配体2-苯基吡啶(ppy)和辅助配体2,2'-联吡啶-3,3’-二羧酸(H2dcbpy)合成了一个铱配合物[Ir(ppy)2(Hdcbpy)],并且测定了其晶体结构。通过对配合物的紫外可见吸收光谱和发光光谱的研究表明,其常温发射位于620nm处,初步推测该磷光发射可能来自由金属到环金属配体和辅助配体的电荷转移(MLCT)跃迁。     

利用吡啶衍生物主配体共轭效应调控铱配合物发光颜色

利用2-苯基吡啶及其衍生物为主配体、四苯基膦酰亚胺为辅助配体合成了3个铱配合物Ir（ppy）₂tpip（Hppy：2-苯基吡啶,Htpip：四苯基膦酰亚胺）、Ir（npy）₂tpip（Hnpy：2-（1-萘基）吡啶）和Ir（pnpy）₂tpip（Hpnpy：2-（9-菲基）吡啶）。它们的结构通过1HNMR和MALDI-TOF质谱进行了表征,其中配合物Ir（ppy）₂tpip还进一步通过晶体结构分析验证。主配体从苯环到萘环和菲环的改变增加了配合物的π共轭,减小了能级差,导致了3种配合物的磷光发射光谱从516nm红移到600和633nm（从绿光到红光）,发光量子效率也从0.36增加到0.51和0.53。从量化计算的结果可以看出,这种共轭效应增加了主配体的电子密度,提高了配合物的LUMO能级。配合物结构和发射性质之间的关系规律为设计不同发光颜色的铱配合物提供了思路。     

含5-(三氟甲基)-2-吡啶甲酸的黄光铱配合物的合成、光物理性质及量化计算研究（英文）

利用环金属化配体2-(2’,4’-二氟苯基)-4-甲基吡啶(dfpmpy)和辅助配体5-(三氟甲基)-2-吡啶甲酸(tfmpic)合成了一个铱配合物[Ir(dfpmpy)2(tfmpic)],并测定了该配合物的光物理和电化学性质。在乙腈溶液中,配合物发射黄色磷光,其最大波长位于554 nm,理论计算表明其磷光来自于金属和环金属化配体到辅助配体或配体间的电荷转移跃迁(3MLCT或3LLCT)。     

室温发光的[2-(3-碘代苯基)吡啶-C^N][2,4-戊二酮]钯(Ⅱ):合成、晶体结构及其光物理性质

本文以2-(3-碘苯基)吡啶(HIppy)为主配体,乙酰丙酮(acac)为辅助配体合成了[2-(3-碘代苯基)吡啶-C^N][2,4-戊二酮-O^O]钯(Ⅱ)[(Ippy)Pd(acac)]配合物,通过核磁、质谱、单晶衍射等数据确定其结构.为了考察碘原子对配合物的光物理性质影响,合成了非碘代的配合物[(ppy)Pd(acac)].单晶结构表明,金属钯与配体形成变形的平面正方形结构,螯合平面C007Pd01N005与O003Pd01O004之间的二面角为3.72°.室温下,配合物(Ippy)Pd(acac)和(ppy)Pd(acac)都具有明显的光致发光(PL)光谱,在四氢呋喃(THF)溶液中两个配合物最大PL光谱在400 nm处,伴随着一个422 nm的肩峰.发光寿命分别为14.9和18.5 ns,我们将室温发光归属于金属微扰配体的单线态(~1LC)荧光.(ppy)Pd(acac)和(Ippy)Pd(acac)在THF溶液中PL量子效率为0.012和0.18,含碘的配合物和不含碘的配合物量子效率相差15倍.可见在配体中的苯环上引入碘原子有效降低了激发态非辐射衰减,从而显著提升了配合物的PL量子效率.相反,在低温77 K下,两个配合物呈现出相同的具有精细结构的PL光谱,发射峰分别在460、484、495和521 nm处,配合物的寿命分别为0.138和0.162 ms,配合物在低温下的发射光谱归属于~3MLCT和~3LC三线态混合的磷光.(Ippy)Pd(acac)在室温时,PL发射光谱的CIE坐标值为(0.169,0.091),是一种色纯度较高的蓝光配合物.     

以3-乙酰基樟脑作为辅助配体的环金属铱配合物的合成及光电性能研究

以立体位阻3-乙酰基樟脑为辅助配体合成了系列新型的环金属铱配合物3-乙酰基樟脑-2-(2,4-二氟)苯基吡啶环金属铱配合物[(46dfppy)₂Ir(acam)], 3-乙酰基樟脑-2-苯基吡啶环金属铱配合物[(ppy)₂Ir(acam)], 3-乙酰基樟脑-2-苯并噻吩吡啶环金属铱配合物[(btp)₂Ir(acam)]. 将配合物的吸收光谱、光致发光光谱以及光致发光效率与辅助配体为乙酰丙酮(acac)的对应配合物进行了比较, 发现在配合物中引入具有大空间位阻的3-乙酰基樟脑使配合物的光致发光效率均有所提高. 并将(ppy)₂Ir(acam)用于有机电致发光器件, 电致发光光谱在516 nm 处有一最大强度峰, 驱动电压为12 V 时最大亮度为10930 cd/m², 最大亮度效率达到14.6 cd/A, 电压为10.7 V 时最大功率为4.23 lm/W, 亮度为698 cd/m².     

铱配合物的电致化学发光性能研究

结构相关的铱配合物[Ir(ppy)2L1](PF6)和[Ir(ppy)2L2](PF6)(ppy=2-苯基吡啶,LI=4-(2,2'-联吡啶-3-乙炔基)-N-(吡啶-2-亚甲基)-N-(噻吩-3-亚甲基)苯胺,L2=4-(2,2'-联吡-3-乙炔基)-N-二(吡啶-2-亚甲基)-苯胺)都具有优良的电致发光(ECL)性...     

Highly phosphorescent bis-cyclometalated iridium complexes: synthesis, photophysical characterization, and use in organic light emitting diodes.

The synthesis and photophysical study of a family of cyclometalated iridium(III) complexes are reported. The iridium complexes have two cyclometalated (C(**)N) ligands and a single monoanionic, bidentate ancillary ligand (LX), i.e., C(**)N2Ir(LX). The C(**)N ligands can be any of a wide variety of organometallic ligands. The LX ligands used for this study were all beta-diketonates, with the major emphasis placed on acetylacetonate (acac) complexes. The majority of the C(**)N2Ir(acac) complexes phosphoresce with high quantum efficiencies (solution quantum yields, 0.1-0.6), and microsecond lifetimes (e.g., 1-14 micros). The strongly allowed phosphorescence in these complexes is the result of significant spin-orbit coupling of the Ir center. The lowest energy (emissive) excited state in these C(**)N2Ir(acac) complexes is a mixture of (3)MLCT and (3)(pi-pi) states. By choosing the appropriate C(**)N ligand, C(**)N2Ir(acac) complexes can be prepared which emit in any color from green to red. Simple, systematic changes in the C(**)N ligands, which lead to bathochromic shifts of the free ligands, lead to similar bathochromic shifts in the Ir complexes of the same ligands, consistent with "C(**)N2Ir"-centered emission. Three of the C(**)N2Ir(acac) complexes were used as dopants for organic light emitting diodes (OLEDs). The three Ir complexes, i.e., bis(2-phenylpyridinato-N,C2')iridium(acetylacetonate) [ppy2Ir(acac)], bis(2-phenyl benzothiozolato-N,C2')iridium(acetylacetonate) [bt2Ir(acac)], and bis(2-(2'-benzothienyl)pyridinato-N,C3')iridium(acetylacetonate) [btp2Ir(acac)], were doped into the emissive region of multilayer, vapor-deposited OLEDs. The ppy2Ir(acac)-, bt2Ir(acac)-, and btp2Ir(acac)-based OLEDs give green, yellow, and red electroluminescence, respectively, with very similar current-voltage characteristics. The OLEDs give high external quantum efficiencies, ranging from 6 to 12.3%, with the ppy2Ir(acac) giving the highest efficiency (12.3%, 38 lm/W, >50 Cd/A). The btp2Ir(acac)-based device gives saturated red emission with a quantum efficiency of 6.5% and a luminance efficiency of 2.2 lm/W. These C(**)N2Ir(acac)-doped OLEDs show some of the highest efficiencies reported for organic light emitting diodes. The high efficiencies result from efficient trapping and radiative relaxation of the singlet and triplet excitons formed in the electroluminescent process.     

Highly phosphorescence iridium complexes and their application in organic light-emitting devices

A new series of iridium(III) mixed ligand complexes TBA[Ir(ppy)(2)(CN)(2)] (1), TBA[Ir(ppy)(2)(NCS)(2)] (2), TBA[Ir(ppy)(2)(NCO)(2)] (3), and [Ir(ppy)(2)(acac)] (4) (ppy = 2-phenylpyridine; acac = acetoylacetonate, TBA = tetrabutylammonium cation) have been developed and fully characterized by UV-vis, emission, IR, NMR, and cyclic voltammetric studies. The lowest energy MLCT transitions are tuned from 463 to 494 nm by tuning the energy of the HOMO levels. These complexes show emission maxima in the blue, green, and yellow region of the visible spectrum and exhibit unprecedented phosphorescence quantum yields, 97 +/- 3% with an excited-state lifetimes of 1-3 micros in dichloromethane solution at 298 K. The near-unity quantum yields of these complexes are related to an increased energy gap between the triplet emitting state and the deactivating e(g) level that have been achieved by meticulous selection of ligands having strong ligand field strength. Organic light-emitting devices were fabricated using the complex 4 doped into a purified 4,4'-bis(carbazol-9-yl)biphenyl host exhibiting a maximum of the external quantum efficiencies of 13.2% and a power efficiency of 37 lm/W for the 9 mol % doped system.     

A cyclometalated iridium(III) complex with enhanced phosphorescence emission in the solid state (EPESS): synthesis, characterization and its application in bioimaging

Iridium(III) complexes with intense phosphorescence in solution have been widely applied in organic light-emitting diodes, chemosensors and bioimaging. However, little attention has been paid to iridium(III) complexes showing weak phosphorescence in solution and enhanced phosphorescence emission in the solid state (EPESS). In the present study, two β-diketonate ligands with different degrees of conjugation, 1-phenyl-3-methyl-4-benzoyl-5-pyrazolone (HL1) and 1-phenyl-3-methyl-4-phenylacetyl-5-pyrazolone (HL2), have been synthesized to be used as ancillary ligands for two iridium(III) complexes, Ir(ppy)(2)(L1) and Ir(ppy)(2)(L2) (Hppy = 2-phenylpyridine). The two complexes have been characterized by single-crystal X-ray crystallography, (1)H NMR and elemental analysis. Interestingly, Ir(ppy)(2)(L1) is EPESS-active whereas Ir(ppy)(2)(L2) exhibits moderately intense emission both in solution and as a neat film, indicating that the degree of conjugation of the β-diketone ligands determines the EPESS-activity. The single-crystal X-ray analysis has indicated that there are π-π interactions between the adjacent ppy ligands in Ir(ppy)(2)(L1) but not in Ir(ppy)(2)(L2). Finally, EPESS-active Ir(ppy)(2)(L1) has been successfully embedded in polymer nanoparticles and used as a luminescent label in bioimaging.     

Exploring synthetic pathways to cationic heteroleptic cyclometalated iridium complexes derived from dipyridylketone

Reactions between 2,2'-dipyridylketone (L1) and different amines gave a series of iminic ligands, and their chemical reductions produced the related amines. The organic ligands were employed in the syntheses of the corresponding new phosphorescent six-member ring bis-cyclometalated heteroleptic iridium(III) complexes of general formula [Ir(ppy)(2)(L)](+) (ppy = 2-phenylpyridine), namely IrLn. The metal complexes containing N-(dipyridin-2-ylmethylene)butan-1-amine (IrL2), N-(dipyridin-2-ylmethyl)butan-1-amine (IrL5), N-(dipyridin-2-ylmethyl)butane-1,4-diamine with amino groups protected by Boc (IrL6-Boc) and TFA (IrL6-TFA), and N-(dipyridin-2-ylmethyl)-N-methylbutan-1-amine (IrL8) were characterized and their electronic and spectroscopic properties interpreted by DFT calculations. Organoiridium complexes containing amines and imines were found to have high and low photoemission quantum yields, respectively, and their features rationalized by quantum mechanic calculations. Some of these complexes show reasonable quantum yields (up to 13%), long lifetime (up to 2.3 μs) and high stability. Complementary and alternative synthetic pathways to get cationic heteroleptic cyclometalated Ir complexes bearing a tethered primary amino group have been explored with the aim to obtain organometallic phosphorescent derivatives suitable for surface functionalization.     

Green and blue electrochemically generated chemiluminescence from click chemistry--customizable iridium complexes

Cationic cyclometalated iridium complexes containing two anionic phenylpyridine (ppy) ligands and the neutral bidentate triazole-pyridine ligand, 2-(1-substituted-1H-1,2,3-triazol-4-yl)pyridine (pytl), were investigated. The complexes display a rich and reversible electrochemical behavior, upon investigations by cyclic voltammetry in strictly aprotic conditions, that couples with excellent emission quantum yields and long lifetimes of the excited states. Therefore, in organic media, all complexes have generated intense green electrochemiluminescence (ECL) through the so-called annihilation procedure and, importantly, a modulation of the emission energy (to blue) has been easily obtained by simple fluorination of the ppy ligand. Finally, taking advantage of their remarkable solubility in water, intense ECL was also obtained from aqueous buffer solutions using the co-reactant method, thus making all the investigated complexes highly promising for their effective use as ECL labels in bioanalytical applications.     

Synthesis and characterization of phosphorescent cyclometalated iridium complexes

The preparation, photophysics, and solid state structures of octahedral organometallic Ir complexes with several different cyclometalated ligands are reported. IrCl3.nH2O cleanly cyclometalates a number of different compounds (i.e., 2-phenylpyridine, 2-(p-tolyl)pyridine, benzoquinoline, 2-phenylbenzothiazole, 2-(1-naphthyl)benzothiazole, and 2-phenylquinoline), forming the corresponding chloride-bridged dimers, CwedgeN2Ir(mu-Cl)2IrCwedgeN2 (CwedgeNis a cyclometalated ligand) in good yield. These chloride-bridged dimers react with acetyl acetone (acacH) and other bidentate, monoanionic ligands such as picolinic acid (picH) and N-methylsalicylimine (salH), to give monomeric CwedgeN2Ir(LX) complexes (LX = acac, pic, sal). The emission spectra of these complexes are largely governed by the nature of the cyclometalating ligand, leading to lambda(max) values from 510 to 606 nm for the complexes reported here. The strong spin-orbit coupling of iridium mixes the formally forbidden 3MLCT and 3pi-pi* transitions with the allowed 1MLCT, leading to a strong phosphorescence with good quantum efficiencies (0.1-0.4) and room temperature lifetimes in the microsecond regime. The emission spectra of the CwedgeN2Ir(LX) complexes are surprisingly similar to the fac-IrCwedgeN3 complex of the same ligand, even though the structures of the two complexes are markedly different. The crystal structures of two of the CwedgeN2Ir(acac) complexes (i.e., CwedgeN = ppy and tpy) have been determined. Both complexes show cis-C,C', trans-N,N' disposition of the two cyclometalated ligands, similar to the structures reported for other complexes with a "CwedgeN2Ir" fragment. NMR data (1H and 13C) support a similar structure for all of the CwedgeN2Ir(LX) complexes. Close intermolecular contacts in both (ppy)2Ir(acac) and (tpy)2Ir(acac) lead to significantly red shifted emission spectra for crystalline samples of the ppy and tpy complexes relative to their solution spectra.     

Synthesis, characteristics and photoluminescent properties of novel Ir-Eu heteronuclear complexes containing 2-carboxyl-pyrimidine as a bridging ligand

Two novel iridium(III) complexes, [Ir(dfppy)(2)(pmc)] and [Ir(ppy)(2)(pmc)] (dfppy = 2-(4',6'-difluoro-phenyl)pyridine, ppy = 1-phenyl-pyridine), were designed and synthesized using 2-carboxyl-pyrimidine (Hpmc) as an ancillary ligand. Single crystals were obtained and characterized by single crystal X-ray diffraction. The tetrametallic complexes {[(C^N)(2)Ir(μ-pmc)](3)EuCl(3)} (C^N = dfppy, ppy) were synthesized using the iridium(III) complexes as "ligands". Photophysical and theoretical studies indicate that [Ir(dfppy)(2)(pmc)] is more suitable for sensitizing the emission of Eu(III) ions than [Ir(ppy)(2)(pmc)].     

Study on a set of bis-cyclometalated Ir(III) complexes with a common ancillary ligand

Bis-cyclometalated iridium(iii) complexes [Ir(F(2)ppy)(2)] (), [Ir(F(2)CNppy)(2)] (), [Ir(DMAF(2)ppy)(2)] () and [Ir(MeOF(2)ppy)(2)] () (F(2)ppy = 4',6'-difluoro-2-phenylpyridinate, F(2)CNppy = 5'-cyano-4',6'-difluoro-2-phenylpyridinate, DMAF(2)ppy = 4',6'-difluoro-4-dimethylamino-2-phenylpyridinate, MeOF(2)ppy = 4',6'-difluoro-4-methyl-2-phenylpyridinate and = 3,5-dimethylpyrazole-N-carboxamide) emitting in the sky blue region were synthesized. We studied the effect of the ancillary ligand and the substituents on the cyclometalating ligands on the crystal structures, photophysical and electrochemical properties and the frontier orbitals. Density functional theory (DFT) calculation results indicate that in and the cyclometalating ligands show negligible participation in the HOMO, the ancillary ligand being the main participant along with the Ir(iii) d-orbitals. exhibits the maximum photoluminescence quantum efficiency and radiative emission rates along with the dominant low frequency metal-ligand vibrations and maximum reorganization energy in the excited state. All the substituted complexes show more polar characteristics than , possessing the highest dipole moment among the complexes. The performances of the solution-synthesised organic light emitting devices (OLEDs) of , and doped in a blend of mCP (m-bis(N-carbazolylbenzene)) and polystyrene are studied.     

Acid-induced degradation of phosphorescent dopants for OLEDs and its application to the synthesis of tris-heteroleptic iridium(III) bis-cyclometalated complexes

Investigations of blue phosphorescent organic light emitting diodes (OLEDs) based on [Ir(2-(2,4-difluorophenyl)pyridine)(2)(picolinate)] (FIrPic) have pointed to the cleavage of the picolinate as a possible reason for device instability. We reproduced the loss of picolinate and acetylacetonate ancillary ligands in solution by the addition of Br?nsted or Lewis acids. When hydrochloric acid is added to a solution of a [Ir(C^N)(2)(X^O)] complex (C^N = 2-phenylpyridine (ppy) or 2-(2,4-difluorophenyl)pyridine (diFppy) and X^O = picolinate (pic) or acetylacetonate (acac)), the cleavage of the ancillary ligand results in the direct formation of the chloro-bridged iridium(III) dimer [{Ir(C^N)(2)(μ-Cl)}(2)]. When triflic acid or boron trifluoride are used, a source of chloride (here tetrabutylammonium chloride) is added to obtain the same chloro-bridged iridium(III) dimer. Then, we advantageously used this degradation reaction for the efficient synthesis of tris-heteroleptic cyclometalated iridium(III) complexes [Ir(C^N(1))(C^N(2))(L)], a family of cyclometalated complexes otherwise challenging to prepare. We used an iridium(I) complex, [{Ir(COD)(μ-Cl)}(2)], and a stoichiometric amount of two different C^N ligands (C^N(1) = ppy; C^N(2) = diFppy) as starting materials for the swift preparation of the chloro-bridged iridium(III) dimers. After reacting the mixture with acetylacetonate and subsequent purification, the tris-heteroleptic complex [Ir(ppy)(diFppy)(acac)] could be isolated with good yield from the crude containing as well the bis-heteroleptic complexes [Ir(ppy)(2)(acac)] and [Ir(diFppy)(2)(acac)]. Reaction of the tris-heteroleptic acac complex with hydrochloric acid gives pure heteroleptic chloro-bridged iridium dimer [{Ir(ppy)(diFppy)(μ-Cl)}(2)], which can be used as starting material for the preparation of a new tris-heteroleptic iridium(III) complex based on these two C^N ligands. Finally, we use DFT/LR-TDDFT to rationalize the impact of the two different C^N ligands on the observed photophysical and electrochemical properties.     

Understanding Electrogenerated Chemiluminescence Efficiency in Blue‐Shifted Iridium(III)‐Complexes: An Experimental and Theoretical Study

Compared to tris(2‐phenylpyridine)iridium(III) ([Ir(ppy)₃]), iridium(III) complexes containing difluorophenylpyridine (df‐ppy) and/or an ancillary triazolylpyridine ligand [3‐phenyl‐1,2,4‐triazol‐5‐ylpyridinato (ptp) or 1‐benzyl‐1,2,3‐triazol‐4‐ylpyridine (ptb)] exhibit considerable hypsochromic shifts (ca. 25–60 nm), due to the significant stabilising effect of these ligands on the HOMO energy, whilst having relatively little effect on the LUMO. Despite their lower photoluminescence quantum yields compared with [Ir(ppy)₃] and [Ir(df‐ppy)₃], the iridium(III) complexes containing triazolylpyridine ligands gave greater electrogenerated chemiluminescence (ECL) intensities (using tri‐n‐propylamine (TPA) as a co‐reactant), which can in part be ascribed to the more energetically favourable reactions of the oxidised complex (M⁺) with both TPA and its neutral radical oxidation product. The calculated iridium(III) complex LUMO energies were shown to be a good predictor of the corresponding M⁺ LUMO energies, and both HOMO and LUMO levels are related to ECL efficiency. The theoretical and experimental data together show that the best strategy for the design of efficient new blue‐shifted electrochemiluminophores is to aim to stabilise the HOMO, while only moderately stabilising the LUMO, thereby increasing the energy gap but ensuring favourable thermodynamics and kinetics for the ECL reaction. Of the iridium(III) complexes examined, [Ir(df‐ppy)₂(ptb)]⁺ was most attractive as a blue‐emitter for ECL detection, featuring a large hypsochromic shift (λ_max=454 and 484 nm), superior co‐reactant ECL intensity than the archetypal homoleptic green and blue emitters: [Ir(ppy)₃] and [Ir(df‐ppy)₃] (by over 16‐fold and threefold, respectively), and greater solubility in polar solvents.