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Three tris-cyclometalated iridium(III) complexes based on different thienopyridazine isomeric ligands were successfully synthesized. The influence of isomerism on material properties was comprehensively evaluated. The thieno[2,3-d]pyridazine based isomeric complexes IrM and IrP have similar photophysical properties. However, sulfur atoms regulate intramolecular hydrogen bonding in complex IrM, leading to differences in other properties. Complex IrM exhibits ambipolar transport properties, good solubility and excellent stability (Td = 425 °C), while IrP shows electronic transport properties, bad solubility and moderate stability (Td = 374 °C). The thieno[3,4-d]pyridazine based complex IrC has very low stability (Td = 214 °C) and significantly reduced optical energy gap compared to other isomers, making it almost non-luminescent. Complexes IrM and IrP are excellent yellow phosphorescent dopants for OLED application, and the maximum power efficiency (PE) and external quantum efficiency (EQE) based on them were 76.0 lm W−1, 26.7% and 73.5 lm W−1, 28.3%, respectively. This indicates that thieno[2,3-d]pyridazine based complexes have great potential for application in full-color displays and solid-state lighting. [ABSTRACT FROM AUTHOR]

A pair of chiral iridium(III) complexes with only ligand chiral centers were successfully synthesized. Strong intramolecular hydrogen bonds exist in these complexes, which improve their stability and luminescence efficiency. All complexes exhibited good thermal stability with Td > 396 °C and nearly unitary PLQYs. The HOMOs of these complexes are mostly located on the chiral auxiliary ligands with a proportion exceeding 62%, which can improve their chiral induction ability. Therefore, their CD spectra display perfect mirror symmetry, and their PL spectra also have apparent circular polarization with dissymmetry factors on the order of 10−3. The circularly polarized organic light-emitting diodes using these chiral emitters exhibit excellent performances with a maximum external quantum efficiency (EQEmax) of 31.9% and intense circularly polarized electroluminescence signals with a dissymmetry factor (‖gEL‖) of up to 3.0 × 10−3. This article proposes a simple material design strategy that takes into account both electroluminescence efficiency and asymmetry factors. [ABSTRACT FROM AUTHOR]

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A new iridium(III) complex Ir(tbt)2(fppz) (2) (fppzH = 2-(3-trifluoromethyl-1H-pyrazol-5-yl)-pyridine) with a triptycenylbenzothiazole (tbt) ligand and its parent complex Ir(bt)2(fppz) (1) with a phenylbenzothiazole (bt) ligand have been synthesized and characterized. The decomposition temperature (Td(5%)) of complex 2 is 395 °C, which is 16 °C higher than that of parent complex 1. Complex 2 showed an emission peak at 546 nm with a PLQY of 67.8%. When compared with complex 1, its luminescent wavelength red-shifted by 11 nm, the PLQY increased by 13% and the luminescent lifetime shortened by 20%. Moreover, the luminescence quenching of complex 2 at a high concentration (30 wt% in PMMA) is found to be effectively prevented, and the PLQY of complex 2 is three times more than that of complex 1. The electron-donating nature of the triptycene scaffold pushes up the HOMO level of complex 2. As a result, complex 2 achieves a higher non-doped device performance, revealing a maximum current efficiency/EQE of 12.6 cd A−1/5.5%, which are obviously higher than that of complex 1 (9.8 cd A−1, 3.8%). The doped device of complex 2 shows a maximum current efficiency/EQE of 29.8 cd A−1/11.8%. These findings suggest that the comprehensive performance of iridium(III) complexes can be obviously improved by the careful introduction of a triptycene scaffold. [ABSTRACT FROM AUTHOR]

A series of charge-neutral cyclometalated iridium(III) complexes (1–3 and 5–7) containing triptycene-substituted ligands (tbt and tpbi) and two parent complexes (4 and 8) were synthesized and characterized. The crystal structures indicated that π–π stacking interactions existed in ligand tbtH, but not in complex 6. However, a large intramolecular repulsion was found in complex 6. These triptycene-based complexes exhibited good thermal stability, which was higher compared with that of the parent complexes. These complexes showed green to yellow emission with peaks that ranged from 503 to 563 nm. The introduction of the rigid non-conjugate triptycene skeleton caused a slight emission red shift (<25 nm), but a significant increase in the PLQYs (>47%) was observed. The electroluminescent devices employing 2 and 6 as phosphors displayed impressive performance improvements and low efficiency roll-off because of the higher PLQYs and HOMO levels of these triptycene-based complexes. The maximum current and external quantum efficiencies of the devices based on complexes 2 and 6 were 41.7 cd A−1, 11.9% and 41.2 cd A−1, 12.6%, respectively, which were about 31% higher than that of the devices based on the parent complexes 4 and 8. This work provides a novel approach to develop highly efficient phosphors with a triptycene skeleton. [ABSTRACT FROM AUTHOR]

It is a challenge to recover lithium from the leaching solution of spent lithium-ion batteries, and crown ethers are potential extractants due to their selectivity to alkali metal ions. The theoretical calculations for the selectivity of crown ethers with different structures to Li ions in aqueous solutions were carried out based on the density functional theory. The calculated results of geometries, binding energies, and thermodynamic parameters show that 15C5 has the strongest selectivity to Li ions in the three crown ethers of 12C4, 15C5, and 18C6. B15C5 has a smaller binding energy but more negative free energy than 15C5 when combined with Li+, leading to that the lithium ions in aqueous solutions will combine with B15C5 rather than 15C5. The exchange reactions between B15C5 and hydrated Li+, Co2+, and Ni2+ were analyzed and the results show that B15C5 is more likely to capture Li+ from the hydrated ions in an aqueous solution containing Li+, Co2+, and Ni2+. This study indicates that it is feasible to extract Li ions selectively using B15C5 as an extractant from the leaching solution of spent lithium-ion batteries. [ABSTRACT FROM AUTHOR]

Eight substituted bidentate Schiff base ligands HOC6H4CH=N-R (HL) (HL1: R = 4-ClC6H4, HL2: R = 2-ClC6H4, HL3: R = 4-NO2C6H4, HL4: R = 4-MeC6H4, HL5: R = 2,6-Me2C6H3, HL6: R = 2,46-Me3C6H2, HL7: R = CH2C6H5, and HL8: R = n-Pr) were synthesized by the typical condensation reaction. Interaction ofcis-[Ru(bpy)2Cl2]⋅2H2O (bpy = 2,2′-bipyridine) with one equivalent of HLligand in the presence of KPF6afforded the cationic ruthenium(II) complexes of the type [Ru(bpy)2(L)](PF6) (1–8). The reaction ofcis-[Ru(phen)2Cl2]⋅2H2O (phen = 1,10-phenanthroline) and HL1under similar condition gave complex [(phen)2Ru(L)](PF6) (1a). Treatment ofcis-[Ru(phen)2Cl2]⋅2H2O with two equivalents of HLin the presence of KPF6resulted in isolation of the cationic ruthenium(III) complexes of the type [Ru(phen)(L)2](PF6) (9-16). All complexes have been spectroscopically characterized. The structures of1a⋅CH2Cl2,2⋅½CH2Cl2,3⋅CH3CN,5⋅½H2O,6,12⋅½HOCH2CH2OH,13⋅CH3CN,15⋅H2O, and16have been determined by single-crystal X-ray diffraction. [ABSTRACT FROM PUBLISHER]

ABSTRACT Chemiluminescence (CL) of a cyclometallated iridium (III) complex {tris[1-(2,6-dimethylphenoxy)-4-(4-chlorophenyl)phthalazine]iridium(III)} in the presence of potassium permanganate and oxalic acid is reported for the first time. Cysteine exhibits sufficient enhancing effect on the CL generated from the cyclometallated iridium(III) complex, which make it possible for the sensitive detection of cysteine using a flow-injection-chemiluminescence (FI-CL) method. The optimum conditions for the chemiluminescence emission were investigated. Under the optimal condition, the linear range for the determination of cysteine was 1.0 × 10-9-5.0 × 10-6 mol/L with a detection limit of 6.9 × 10-10 mol/L. A relative standard deviation of 1.6% was obtained for eight replicate determinations. The mechanisms of CL are proposed and the emitting species was identified as the metal-to-ligand charge-transfer (MLCT) excited states of the iridium complex. Copyright © 2011 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

ABSTRACT A novel chemiluminescence (CL) system, including the cyclometallated iridium(III) complex {tris[1-(2,6-dimethylphenoxy)-4-(4-chlorophenyl)phthalazine]iridium}, potassium permanganate and oxalic acid, is proposed for the determination of benzenediols. This method is based on the fact that hydroquinone and catechol exhibited an inhibiting effect, while resorcinol exhibited an enhancing effect on CL intensity. The optimum conditions for CL emission were investigated. Under optimal conditions, the detection limits of hydroquinone, catechol and resorcinol were 6.4 × 10−8, 2.7 × 10−9 and 8.1 × 10−7 mol/L, respectively. The method has been successfully applied to the determination of benzenediols in different types of water sample. The luminophors of the CL systems were all identified as the metal-ligand charge-transfer (MLCT) excited state of the iridium complex. Copyright © 2011 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Four red homoleptic iridium (III) complexes (Ir1 – Ir4) with steric phenylphthalazine ligands have been synthesized. Single X-ray structural analysis shows that the steric hindrance groups can prevent molecular aggregation. All complexes exhibited red emission with peaks between 614 and 629 nm in CH 2 Cl 2 and photoluminescence quantum yields (QYs) of 44%–86% in doped films. They were concentration-insensitive, their QYs in neat powder and air atmosphere can reach a maximum of 15%. These complexes exhibited excellent thermal stability with T d higher than 416 °C. The OLEDs based on these complexes showed good performances at 10 wt% high doping concentration. Especially, the device based on Ir1 gave a peak current efficiency and external quantum efficiency (EQE) of 25.0 cd A−1 and 24.2% with mild efficiency roll-off, which is the most efficient OLED based on phthalazine iridium complexes. The maximum EQEs of non-doped devices are between 4.0% and 5.6%, which are considerably high, compared with the reported efficiency of iridium complexes based red-emitting non-doped devices. These studies show that increasing the density of the rigid steric groups of iridium complexes is very effective to achieve high efficiency and low concentration sensitive red phosphorescent devices. Complex Ir1 exhibited the highest PLQYs of 0.86, T d of 419 °C and peak EQE 24.2%. [Display omitted] • 1, Four homoleptic Ir complexes with enhanced steric hindrance were synthesized. • 2, All complexes exhibited excellent thermal stability with T d higher than 416 °C. • 3, These complexes are red emitting and have high color purity. • 4, All complexes are concentration-insensitive with high QYs in neat films. • 5, The best device exhibited an EQE max of 24.2% with mild efficiency roll-off. [ABSTRACT FROM AUTHOR]

AIE complex Pt3 exhibits high OLED efficiencies of 16.0cd A-1, 7.4% and low efficiency roll-off. [Display omitted] • Three Pt(II) complexes containing diazafluorene-based ligands were synthesized. • All these complexes exhibited AIE properties. • Substituents significantly affect the aggregation and properties of Pt complexes. • The doped device of Pt3 shows maximum efficiencies of 16.0 cd A-1 and 7.4%. • The nondoped device EQE of Pt3 (2.4%) is higher than Pt2 (1.6%). Three neutral Pt(II) complexes (Pt1 - Pt3) containing diazafluorene derivative ligands have been designed and synthesized. Single-crystal diffractions analysis of complex Pt2 revealed that there are strong Pt-Pt interactions in crystal phase. All these complexes exhibited AIE properties. Moreover, the luminescence spectra of these complexes change significantly with the change of their aggregation state. From complexes Pt1 to Pt3 , their PL QYs in neat films increases from 0.7% to 34.6%, indicating the important role of steric groups in reducing concentration quenching. For non-doped OLEDs, complex Pt3 was markedly superior to complex Pt2 with the emission peak at 608 nm, maximum CE of 8.0 cd A-1, maximum EQE of 2.4% and maximum luminance of 2229 cd m−2, attributed to the charge-carries transporting capability of ECAF ligand. Complex Pt3 exhibited medium performance in doped OLEDs with a maximum CE of 16.0 cd A-1, a maximum EQE of 7.4%, a maximum luminance of 15409 cd m−2 and low efficiency roll-off. These studies clearly illustrate that regulating the steric hindrance and carrier transport properties of ligands plays an important role in improving the electroluminescent properties of Pt(II) complexes. [ABSTRACT FROM AUTHOR]

The high device efficiencies of 50.5 cd A−1 and 14.9% for device B were achieved, which are 21% and 42% higher than that of device A, respectively. At the luminance of 60,000 cd m−2, the efficiency roll off value of device B (64%) is smaller than that of device A (70%). The better performance of device B is attributed to the bicyclo [2.2.2] oct-2-ene group. • A series of iridium complexes 1–4, has been easily synthesized, complexes 2 and 4 containing steric groups. • Using complexes 2 and 4 as dopant, the OLEDs show good performance at 2.5 wt% doping concentration. • Device based on complex 4 containing steric groups displays the highest peak luminance of 105689 cd m−2, and exhibits a maximum current efficiency of 50.5 cd A−1 and a maximum external quantum efficiency of 14.9% with small efficiency roll-off values. Four bis-cyclometalated iridium complexes (Ir(tpp) 2 (pic) (1) , Ir(tpp) 2 (paz) (2) , (Ir(ttp) 2 (pic) (3) and (Ir(ttp) 2 (paz) (4) with phenylpyridazine derivative ligands were synthesized under mild reaction conditions, in which tpp (tppH = 3, 6-bis(4- (trifluoromethyl)phenyl)pyridazine) or ttp (ttpH = (5 s, 8 s)-1,4-bis(4- (trifluoromethyl))-diphenyl-5,6,7,8-tetrahydro-5,8-thanophthalazine) was used as the primary ligand and pyridine-2-carboxylate (pic) or paz (pazH = 2-(3-(trifluoromethyl)-1H-pyrazol-5-yl)pyridine) were used as ancillary ligand. The coordination arrangement of complexes 1 – 3 was revealed by the single X-ray structural analyses. All complexes showed strong emissions with peaks ranged from 519 to 547 nm and quantum efficiencies of 0.55–0.80. By introducing sterically hindered bicyclo [2.2.2] oct-2-ene groups in the primary ligands of complexes 3 and 4 , their molecular interactions are strongly restrained in solid. The organic light-emitting diodes (OLEDs) were fabricated with complexes 2 (device A) and 4 (device B) as dopants. The better device performances with a maximum current efficiency of 50.5 cd A−1 and a maximum external quantum efficiency of 14.9% are achieved by device B, along with smaller efficiency roll-off, which is attributed to the effect of alkyl steric groups and relative more matched energy levels in device. [ABSTRACT FROM AUTHOR]

Complex 2 exhibited the highest PLQYs of 0.53, Td of 348 °C and peak EQE 14.4%. • Unusual neutral Ir(III) complexes with two C∧N∧N ligands were synthesized. • The structure-property relationship in these complexes had been revealed. • The CF 3 substituted complex 2 exhibited the best PLQYs of 0.53 and T d of 348 °C. • The yellow device based on 2 gave a peak external quantum efficiency of 14.4%. Four bis-tridentate iridium(III) complexes with two different C∧N∧N-coordinating ligands have been synthesized and characterized. All complexes exhibited yellow/orange emission peaking at 580–604 nm with short lifetimes of 1.4–1.6 μs and medium photoluminescence quantum yields (PLQYs) of 31%–53%. These complexes exhibit good thermal stability with decomposition temperature (T d) exceeding 310 °C. The luminescence efficiency and thermal stability of iridium complexes were improved by the m -substituted CF 3 groups. As a result, complex 2 exhibited the highest PLQYs of 0.53 and T d of 348 °C. The OLEDs based on complex 2 showed good performances. The device at 2% doping concentration showed a maximum current efficiency of 36.4 cd A−1, power efficiency of 29.1 lm W−1 and external quantum efficiency (EQE) of 14.4%. These results suggest that these complexes have potential for the application in high-efficiency OLEDs. [ABSTRACT FROM AUTHOR]

Two one-pot methods have been used to synthesize various homoleptic phenylpyridazine iridium (III) complexes (2 – 4). The coordination arrangements of 2 and 3 were revealed by carrying out single X-ray structural analyses. These complexes showed green emission. Their peak wavelengths ranged from 508 to 538 nm with quantum yields greater than 70%. Density functional theory (DFT) was used to discuss the correlation between substituent nature and photophysical characteristics of these complexes. Organic light-emitting diodes (OLEDs) were fabricated by taking 2 – 4 as dopants. The green device based on complex 4 shows a maximum current efficiency and external quantum efficiency of 78.6 cd A−1 and 21.9%, respectively, and mild efficiency roll-off. The results suggest that these homoleptic phenylpyridazine iridium(III) complexes have potential application as efficient emitters in OLEDs. OLED based on blue phosphor 4 shows promising luminance over 100000 cd m−2 and luminous efficiencies of 21.9%, 78.6 cd A−1 with CIE of (0.40, 0.58). Image 1 • Three homoleptic phenylpyridazine iridium(III) complexes were synthesized by two one-pot methods by improving ligand reactivity. • Complex 4 emitted 538 nm green light with 99% QY. OLED based on it shows luminous efficiencies of 21.9% and 78.6 cd A−1. • The structure-property relationship in these complexes had been revealed. [ABSTRACT FROM AUTHOR]

• Three di-orthometallated triphenyl phosphite iridium complexes have been synthesized. • The OLEDs based on them show good performance at 15 wt% high doping concentration. • Device C displays peak luminance and LE of 15990 cd m−2, and 31.5 cd A−1. A series of di-orthometallated triphenyl phosphite iridium(III) complexes [Ir(tdbpit)(bpy)Cl (1), Ir(tdbpit)(dbbpy)Cl (2), Ir(tdbpit)(sb)Cl (3) (tdbpitH 2 = tris (2,4-di- tert -butylphenyl) phosphite, bpy = 2,2′-bipyridine, dbbpy = 4,4′-diterbutyl-2,2′-bipyridine, sb = 4,5-diaza-9,9′-spirobifluorene)] with steric groups had been synthesized and characterized. Single X-ray structural analyses were conducted on 2 and 3 to reveal their coordination arrangement. In CH 2 Cl 2 solution, complexes 1 – 3 show strong yellow-green phosphorescent emission at 569 nm, 562 nm and 559 nm, respectively. The observed emission lifetimes are between 1.39 μs and 1.54 μs, together with quantum yields between 0.31 and 0.63 in PMMA film. The extra steric groups on the diimine ligands had obviously increased the quantum yields by decreasing the intermolecular interaction. Using these iridium(III) complexes as dopant, the OLEDs show good performance at 15 wt% high doping concentration. OLED device based on complex 2 shows the highest luminous efficiencies of (10.1%, 32.5 cd A−1). Device based on complex 3 displays the highest peak luminance of 15990 cd m−2, and exhibits a maximum luminous efficiency of 31.5 cd A−1 with an external quantum efficiency of 9.6% and small efficiency roll-off values. At a practical luminance of 1000 cd m−2, the efficiency values are maintained as high as 9.0% and 29.5 cd A−1. The results show that the sterically hindered tert butyl and spirofluorene spacers in these phosphor molecules can effectively reduce the self-quenching. [ABSTRACT FROM AUTHOR]

A series of charge-neutral cyclometalated iridium(iii) complexes (1-3 and 5-7) containing triptycene-substituted ligands (tbt and tpbi) and two parent complexes (4 and 8) were synthesized and characterized. The crystal structures indicated that π-π stacking interactions existed in ligand tbtH, but not in complex 6. However, a large intramolecular repulsion was found in complex 6. These triptycene-based complexes exhibited good thermal stability, which was higher compared with that of the parent complexes. These complexes showed green to yellow emission with peaks that ranged from 503 to 563 nm. The introduction of the rigid non-conjugate triptycene skeleton caused a slight emission red shift (<25 nm), but a significant increase in the PLQYs (>47%) was observed. The electroluminescent devices employing 2 and 6 as phosphors displayed impressive performance improvements and low efficiency roll-off because of the higher PLQYs and HOMO levels of these triptycene-based complexes. The maximum current and external quantum efficiencies of the devices based on complexes 2 and 6 were 41.7 cd A -1 , 11.9% and 41.2 cd A -1 , 12.6%, respectively, which were about 31% higher than that of the devices based on the parent complexes 4 and 8. This work provides a novel approach to develop highly efficient phosphors with a triptycene skeleton.

A new phosphorescent chemosensor for Hg(2+) and acetonitrile (MeCN) based on iridium(III) complex Ir(dpp)(2)(dtc) (Ir1, dppH = 4,6-diphenylpyrimidine, dtcH = diethyl dithiocarbamic acid) was realized. Upon addition of a tetrahydrofuran (THF) solution of Hg(2+), the dichloromethane (DCM) solution of Ir1 gave a visual color change and significant fluorescent quenching. When MeCN was added, a new fluorescent emission emerged, which constituted a selective MeCN phosphorescent chemosensor. Complex Ir1 has been developed as an AND logic gate with Hg(2+) and MeCN as inputs.

Chemiluminescence (CL) of a cyclometallated iridium (III) complex {tris[1-(2,6-dimethylphenoxy)-4-(4-chlorophenyl)phthalazine]iridium(III)} in the presence of potassium permanganate and oxalic acid is reported for the first time. Cysteine exhibits sufficient enhancing effect on the CL generated from the cyclometallated iridium(III) complex, which make it possible for the sensitive detection of cysteine using a flow-injection-chemiluminescence (FI-CL) method. The optimum conditions for the chemiluminescence emission were investigated. Under the optimal condition, the linear range for the determination of cysteine was 1.0 × 10(-9) -5.0 × 10(-6)  mol/L with a detection limit of 6.9 × 10(-10)  mol/L. A relative standard deviation of 1.6% was obtained for eight replicate determinations. The mechanisms of CL are proposed and the emitting species was identified as the metal-to-ligand charge-transfer (MLCT) excited states of the iridium complex., (Copyright © 2011 John Wiley & Sons, Ltd.)

A novel chemiluminescence (CL) system, including the cyclometallated iridium(III) complex {tris[1-(2,6-dimethylphenoxy)-4-(4-chlorophenyl)phthalazine]iridium}, potassium permanganate and oxalic acid, is proposed for the determination of benzenediols. This method is based on the fact that hydroquinone and catechol exhibited an inhibiting effect, while resorcinol exhibited an enhancing effect on CL intensity. The optimum conditions for CL emission were investigated. Under optimal conditions, the detection limits of hydroquinone, catechol and resorcinol were 6.4 × 10(-8), 2.7 × 10(-9) and 8.1 × 10(-7)  mol/L, respectively. The method has been successfully applied to the determination of benzenediols in different types of water sample. The luminophors of the CL systems were all identified as the metal-ligand charge-transfer (MLCT) excited state of the iridium complex., (Copyright © 2011 John Wiley & Sons, Ltd.)