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...     

以2，2′-联嘧啶为副配体的铱配合物的合成、晶体结构和发光性质研究

利用环金属配体2-(4',6'-二氟苯基)吡啶(dfppy)和副配体2,2'-联嘧啶(bpm)合成了一个铱配合物[Ir(dfppy)z(bpm)]Cl,通过1H NMR,质谱,元素分析及红外光谱对其进行了表征,并且测定了其晶体结构.同时利用得到的中间配合物[Ir(dfppy):(bpm)] [Ir(dfppy)2(Cl)2]n晶体结构讨论了配合物形成过程.对配合物[Ir(dfppy)2(bpm)]Cl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609 nm处,初步推测该磷光发射可能来自金属到配体的电荷转移(MLCT)跃迁和配体自身,π→π*跃迁(LC)的混合.     

室温磷光材料二(2-苯基吡啶)(2-(2-吡啶)苯并咪唑)合铱(III)的合成及光电特性

以2-苯基吡啶(ppy)为主配体, 2-(2-吡啶)苯并咪唑(pybiH)为辅助配体合成了一种室温蓝绿色磷光发射材料二(2-苯基吡啶)( 2-(2-吡啶)苯并咪唑)合铱(III) ((ppy)₂Ir(pybi)), 通过傅里叶变换红外(FTIR)光谱、核磁共振氢谱(1H NMR)、质谱(MS)、元素分析对其结构进行了表征. 利用紫外-可见吸收光谱、荧光激发和发射光谱、循环伏安曲线, 结合含时密度泛函理论(TD-DFT)模拟计算研究了(ppy)₂Ir(pybi)的光物理特性及能级结构, 并研究了其电致发光性能. (ppy)₂Ir(pybi)的紫外吸收峰分别位于250, 295, 346和442 nm, 与理论模拟计算吻合得很好;(ppy)₂Ir(pybi)为蓝绿光发射, 发光峰分别位于495 和518 nm; (ppy)₂Ir(pybi) 的最高占据轨道(HOMO)和最低空轨道(LUMO)能级分别为-6.11和-3.43 eV, 光学带隙为2.68 eV; 以(ppy)₂Ir(pybi)为掺杂剂, 4,4'-N,N'-二咔唑基联苯(CBP)为主体材料, 制备电致磷光器件, 电致发射峰位于508 nm, 最大亮度为8451 cd·m^-2, 最大电流效率为17.6 cd·A^-1. 这些研究为(ppy)₂Ir(pybi)在有机电致发光领域的应用提供实验依据.     

以苯基吡唑为主配体的Ir配合物电子结构和光谱性质的密度泛函理论研究

用密度泛函理论(DFT)和含时密度泛函理论(TD-DFT)的B3LYP方法对以苯基吡唑ppz为主配体的4种Ir配合物Ir(ppz)₃, Ir(ppz)₂(acac), Ir(ppz)₂(pic)和Ir(ppz)₂(dbm)的电子结构和光谱性质进行了理论研究. 计算结果表明, 辅助配体的改变对Ir配合物的最高占据轨道(HOMO)的影响不大, 但会显著的降低分子最低空轨道(LUMO)的能级, 从而调节Ir配合物的HOMO和LUMO间的能隙. 4种配合物对应的发射跃迁分别为Ir(ppz)₃:d(Ir)+π(ppz)→π*(ppz); Ir(ppz)₂(pic):d(Ir)+(ppz)→π*(pic); Ir(ppz)₂(acac), Ir(ppz)₂(dbm):d(Ir)+π(acacdbm)→π*(acacdbm). 金属配合物的发光颜色可以通过选择合适的辅助配体调节.     

三氟甲基取代Ir配合物的电子结构和磷光性质的理论研究

采用密度泛函理论m PW1PW91方法研究了三氟甲基(CF3)基团修饰的一类Ir磷光材料,即Ir(C∧C)(ppy)2、Ir(C∧C)(ppy)(Ort CF3)、Ir(C∧C)(ppy)(Me CF3)和Ir(C∧C)(ppy)(Par CF3)[(C∧C:3-甲基-1-(2,4-甲基苯)-1H-咪唑;ppy:2-苯基吡啶,Ort CF3=2-(2-(三氟甲基)苯基)吡啶;Me CF3:2-(3-(三氟甲基)苯基)吡啶;Par CF3:2-(4-(三氟甲基)苯基)吡啶]的电子结构和光学性质.理论计算得到Ir(C∧C)(ppy)2的电子结构、吸收光谱和磷光光谱与实验结果吻合得较好.通过与实验分子Ir(C∧C)(ppy)2对比,向ppy的邻位和对位引入CF3基团加强金属和配体之间的作用力,提高空穴和电子注入能力,吸收和磷光发射光谱发生红移.尤其,Ir(C∧C)(ppy)-(Ort CF3)比其他配合物在发射磷光时金属到配体的电荷转移(3MLCT)的贡献大、跃迁偶极矩(μS1)大、d轨道能级分裂大,并且单三重态分裂能(ΔES1-T1)小,这表明设计的分子Ir(C∧C)(ppy)(Ort CF3)有望成为好的磷光发光材料.     

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。     

利用静电吸引作用提高光催化放氢效率

本文设计合成了两个分别带正电荷和负电荷的Ir(Ⅲ)配合物[Ir(ppy)₂(bpy)]⁺(ppy=2-苯基吡啶,bpy=2,2′-联吡啶)和[Ir(ppy)₂(pbs)]^-(pbs=1,10-菲啰啉-4,7-二苯磺酸钠)作为光敏剂,以[Co(bpy)₃]²⁺为放氢催化剂,比较了Ir(Ⅲ)配合物的光催化放氢效率.发现带负电荷的Ir(Ⅲ)配合物具有更高的光催化放氢效率,带负电荷光敏剂和带正电荷催化剂间的静电吸引可能对放氢效率的提高起到了重要作用.     

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.     

新型铱配合物的合成及电致发光性质研究

合成了一种新型橙红色磷光材料铱的配合物(npp)₂Ir(acac)(npp=2-(1-萘基)-4-苯基吡啶，acac=乙酰丙酮)，通过 ¹H NMR、MS、元素分析对其结构进行了表征。以铱配合物(npp)₂Ir(acac)作为发光体，制备了结构为ITO/Ir(5%)：PVK(60 nm)/F-TBB(15 nm)/Alq₃(15 nm)/LiF(1 nm)/Al(150 nm)的电致发光器件，研究了其电致发光性质。结果表明器件的最大发射波长在599 nm，最大发光亮度为3 841 cd·m^-2，最大电流效率达3.9 cd·A^-1。     

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。     

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)].     

2-苯基吡啶铱(Ⅲ)配合物及其衍生物光谱性质的理论研究

采用密度泛函理论B3PW91和UB3PW91方法, 分别对4种Ir(Ⅲ)配合物(ppy)₂Ir(acac)(1, ppy=2-苯基吡啶, acac=乙酰丙酮)、(npy)₂Ir(acac)(2, npy=2-萘-1-基吡啶)、(pq)₂Ir(acac)(3, pq=2-苯基喹啉)和(bzq)₂Ir(acac)(4, bzq=苯并喹啉)进行了基态和激发态的几何优化, 在此基础上用TD-DFT方法计算了吸收和发射光谱. 结果表明, 随着ppy配体上并苯环位置的变化, 参与最大吸收和发射的分子轨道能隙降低程度不同, 从而使配合物2, 3, 4的最大吸收和发射光谱都比配合物1发生红移, 其中在吡啶环上增加苯环对吸收光谱的影响最大. 这4个分子最大吸收波长的顺序为1<2<4<3, 而最大发射波长顺序则是1<4<3<2. 由于配合物2的两个苯环上H的强排斥作用降低了其共轭程度, 使分子发生很大程度的扭曲, 导致其斯托克位移最大.     

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.     

Synthetic control of excited-state properties in cyclometalated Ir(III) complexes using ancillary ligands

The synthesis and photophysical characterization of a series of (N,C(2')-(2-para-tolylpyridyl))2 Ir(LL') [(tpy)2 Ir(LL')] (LL' = 2,4-pentanedionato (acac), bis(pyrazolyl)borate ligands and their analogues, diphosphine chelates and tert-butylisocyanide (CN-t-Bu)) are reported. A smaller series of [(dfppy)2 Ir(LL')] (dfppy = N,C(2')-2-(4',6'-difluorophenyl)pyridyl) complexes were also examined along with two previously reported compounds, (ppy)2 Ir(CN)2- and (ppy)2 Ir(NCS)2- (ppy = N,C(2')-2-phenylpyridyl). The (tpy)2 Ir(PPh2CH2)2 BPh2 and [(tpy)2 Ir(CN-t-Bu)2](CF3SO3) complexes have been structurally characterized by X-ray crystallography. The Ir-C(aryl) bond lengths in (tpy)2 Ir(CN-t-Bu)2+ (2.047(5) and 2.072(5) A) and (tpy)2 Ir(PPh2CH2)2 BPh2 (2.047(9) and 2.057(9) A) are longer than their counterparts in (tpy)2 Ir(acac) (1.982(6) and 1.985(7) A). Density functional theory calculations carried out on (ppy)2 Ir(CN-Me)2+ show that the highest occupied molecular orbital (HOMO) consists of a mixture of phenyl-pi and Ir-d orbitals, while the lowest unoccupied molecular orbital is localized primarily on the pyridyl-pi orbitals. Electrochemical analysis of the (tpy)2 Ir(LL') complexes shows that the reduction potentials are largely unaffected by variation in the ancillary ligand, whereas the oxidation potentials vary over a much wider range (as much as 400 mV between two different LL' ligands). Spectroscopic analysis of the cyclometalated Ir complexes reveals that the lowest energy excited state (T1) is a triplet ligand-centered state (3LC) on the cyclometalating ligand admixed with 1MLCT (MLCT = metal-to-ligand charge-transfer) character. The different ancillary ligands alter the 1MLCT state energy mainly by changing the HOMO energy. Destabilization of the 1MLCT state results in less 1MLCT character mixed into the T1 state, which in turn leads to an increase in the emission energy. The increase in emission energy leads to a linear decrease in ln(k(nr)) (k(nr) = nonradiative decay rate). Decreased 1MLCT character in the T1 state also increases the Huang-Rhys factors in the emission spectra, decreases the extinction coefficient of the T1 transition, and consequently decreases the radiative decay rates (k(r)). Overall, the luminescence quantum yields decline with increasing emission energies. A linear dependence of the radiative decay rate (k(r)) or extinction coefficient (epsilon) on (1/deltaE)2 has been demonstrated, where deltaE is the energy difference between the 1MLCT and 3LC transitions. A value of 200 cm(-1) for the spin-orbital coupling matrix element 3LC absolute value(H(SO)) 1MLCT of the (tpy)2 Ir(LL') complexes can be deduced from this linear relationship. The (fppy)2 Ir(LL') complexes with corresponding ancillary ligands display similar trends in excited-state properties.     

Exploring Excited‐State Tunability in Luminescent Tris‐cyclometalated Platinum(IV) Complexes: Synthesis of Heteroleptic Derivatives and Computational Calculations

The synthesis, structure, electrochemistry, and photophysical properties of a series of heteroleptic tris‐ cyclometalated Pt^IV complexes are reported. The complexes mer‐[Pt(C^N)₂(C′^N′)]OTf, with C^N=C‐deprotonated 2‐(2,4‐difluorophenyl)pyridine (dfppy) or 2‐phenylpyridine (ppy), and C′^N′=C‐deprotonated 2‐(2‐thienyl)pyridine (thpy) or 1‐phenylisoquinoline (piq), were obtained by reacting bis‐ cyclometalated precursors [Pt(C^N)₂Cl₂] with AgOTf (2 equiv) and an excess of the N′^C′H pro‐ligand. The complex mer‐[Pt(dfppy)₂(ppy)]OTf was obtained analogously and photoisomerized to its fac counterpart. The new complexes display long‐lived luminescence at room temperature in the blue to orange color range. The emitting states involve electronic transitions almost exclusively localized on the ligand with the lowest π–π* energy gap and have very little metal character. DFT and time‐dependent DFT (TD‐DFT) calculations on mer‐[Pt(ppy)₂(C′^N′)]⁺ (C′^N′=thpy, piq) and mer/fac‐[Pt(ppy)₃]⁺ support this assignment and provide a basis for the understanding of the luminescence of tris‐cyclometalated Pt^IV complexes. Excited states of LMCT character may become thermally accessible from the emitting state in the mer isomers containing dfppy or ppy as chromophoric ligands, leading to strong nonradiative deactivation. This effect does not operate in the fac isomers or the mer complexes containing thpy or piq, for which nonradiative deactivation originates mainly from vibrational coupling to the ground state.     

Theoretical studies of blue-emitting iridium complexes with different ancillary ligands

The structural and electronic properties of two heteroleptic iridium complexes Ir(dfppy)2(pic) (FIrpic) and Ir(dfppy)2(acac) (FIracac) have been investigated theoretically, where dfppy = 2-(2,4-difluorophenyl) pyridine, pic = picolinic acid, and acac = acetoylacetonate. The geometries of ground and excited states are optimized at PBE0/LANL2DZ and CIS/LANL2DZ levels, respectively. Time-dependent density functional theory (TDDFT) method is employed to explore the absorption and emission properties. In the ground state, the highest-occupied molecular orbital has a significant mixture of metal Ir(d) and dfppy(pi), the lowest-unoccupied orbital locates primarily on pi* of pic for FIrpic and pi* of dfppy for FIracac. The luminescence of each complex originates from the lowest triplet excited state, which is assigned to the mixing of metal-to-ligand charge transfer and intraligand charge transfer characters. The effects of ancillary ligands pic and acac on absorption and emission spectra are observed by analysis of TDDFT results. The connection between the nature of excited states and the behavior of the complexes with different ancillary ligands is elucidated.     

Photophysical Properties of Heteroleptic Iridium Complexes Containing Carbazole‐Functionalized β‐Diketonates

Twelve iridium complexes with general formula of Ir(C^N)₂(LX) [C^N represents the cyclometalated ligand, i.e. 2‐(2,4‐difluorophenyl) pyridine (dfppy), 2‐phenylpyridine (ppy), dibenzo{f, h}quinoxaline (DBQ); LX stands for β‐diketonate, i.e. acetyl acetonate (acac), 1‐(carbazol‐9‐yl)‐5,5‐dimethylhexane‐2,4‐diketonate (CBDK), 1‐(carbazol‐9‐yl)‐5,5,6,6,7,7,7‐heptafluoroheptane‐2,4‐diketonate (CHFDK), 1‐(N‐ethyl‐carbazol‐3‐yl)‐4,4,5,5,6,6,6‐heptafluorohexane‐1,3‐diketonate (ECHFDK)] are synthesized, characterized and their photophysical properties are systemically studied. In addition, crystals of Ir(DBQ)₂(CHFDK) and Ir(DBQ)₂(acac) are obtained and characterized by single crystal X‐ray diffraction. The choice of these iridium complexes provides an opportunity for tracing the effect of the triplet energy level of ancillary ligands on the photophysical and electrochemical behaviors. Data show that if the triplet energy level of the β‐diketonate is higher than that of the Ir(C^N)₂ fragment and there is no superposition on the state density map, strong ³LC or ³MLCT‐based phosphorescence can be obtained. Alternatively, if the state density map of the two parts are in superposition, the ³LC or ³MLCT‐based transition will be quenched at room temperature. Density functional theory calculations show that these complexes can be divided into two categories. The lowest excited state is mainly determined by C^N but not β‐diketonate when the difference between the triplet energy levels of the two parts is large. However, when this difference is very small, the lowest excited state will be determined by both sides. This provides a satisfactory explanation for the experimental observations.     

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.