一种双核铕配合物的合成、光致发光和电致发光性质研究

合成了一个新的双核铕配合物Eu(TTA)₃(tpphz)Eu(TTA)₃(其中TTA＝去质子化的α-噻吩甲酰三氟丙酮; tpphz＝[3,2-a:2',3'-c:3',2'-h:2'',3''-j]四吡啶基吩嗪). 研究了该配合物的光致发光和电致发光性质. 一个四层电致发光器件ITO/TPD, 10 nm/Eu(TTA)₃(tpphz)Eu(TTA)₃, 20 nm/BCP, 20 nm/AlQ, 40 nm/Mg_0.9Ag_0.1, 200 nm/Ag, 100 nm表现出中心在633 nm处的宽带红光发射, 该宽带发射可能来源于双核Eu(III)配合物和TPD形成的激基复合物. 该器件的启动电压为10 V, 在18 V和135 mA/cm²时的最大亮度达146 cd/m².     

Luminescence Investigations on Eu(III) Thenoyltrifluoroacetonate Complexes with Amide Ligands

The influence of amide ligands on the photoluminescent behavior of tris(thenoyltrifluoroacetonate)- europium(III) in the solid state is reported. Elemental analysis showed that these compounds have the following formulas [Eu(TTA)₃·(ANL)₂] and [Eu(TTA)₃·PZA], where ANL = acetanilide and PZA = pyrazinamide. The photoluminescence spectra of the complexes recorded in the range 420-720 nm at 77 K show narrow bands arising from the ⁵D₀ → ⁷F _J transitions (where J = 0-4), under excitation at 394 nm. Based on the emission spectra and luminescence decay curves the intensity parameters (Ω_λ), lifetime (τ) and emission quantum efficiency (η) were determined. The Ω₂ values indicate that the Eu³⁺ion in these complexes is in a highly polarizable chemical environment. The higher value of η (60%) obtained for the complex with the ANL ligand, in comparison with the complex with the PZA ligand (30%), indicates a more efficient deactivation of the Eu³⁺ion in the [Eu(TTA)₃·PZA] complex.     

Efficient Pyrazolo[5,4-f]quinoxaline Functionalized Os(II) Based Emitter with an Electroluminescence Peak Maximum at 811 nm

Upon fusing the pyrazinyl pyrazole entity in giving pyrazolo[3,4-f]quinoxaline chelate, the corresponding Os(II) based NIR emitter exhibited “invisible” and efficient electroluminescence with a peak maximum at 811 nm. A maximum external quantum efficiency of 0.97 % and a suppressed efficiency roll-off till a current density of 300 mA cm⁻² was also exhibited.     

Synthesis, characterization and photophysics of fluorene-alt-oxadiazole copolymers containing pendent iridium (III) complex moiety

A series of fluorene-alt-oxadiazole copolymers containing a pendent phosphor chromophore of the (piq)₂Ir(pic) complex were synthesized via the palladium-catalyzed Suzuki coupling reaction, where piq is 1-phenylisoquinoline and pic is picolinic acid. These copolymers exhibited a similar absorption spectrum with a peak at about 330 nm and a typical emission peak at 408 nm in CH₂Cl₂ from the fluorene-alt-oxadiazole backbone. However, a significantly red-shifted emission peak at about 625 nm was observed in the neat films of these copolymers, which are attributed to the pendent iridium (III) complex unit. Using these copolymers as single emission layer, the polymer light-emitting devices with a configuration of ITO/PEDOT:PSS/copolymers/LiF/Al exhibited a saturated red emission with a peak at 632 nm. Significant influence of the attached iridium (III) complex ratio on EL performance was presented. A maximum current efficiency of 1.2 cd/A at 63 mA/cm² and a maximum luminance of 1125 cd/m² at 12 V were achieved from the device with the copolymer containing iridium (III) complex in a 3% molar ratio.     

N-Heterocyclic Carbene Analogues of Nucleophilic Phosphinidene Transition Metal Complexes

Chloride abstraction from the complexes [(η⁶-p-cymene){(IDipp)P}MCl] ( 2 a , M=Ru; 2 b , M=Os) and [(η⁵-C₅Me₅){(IDipp)P}IrCl] ( 3 b , IDipp=1,3-bis(2,6-diisopropylphenyl)imidazolin-2-ylidene) with sodium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate (NaBAr^F) in the presence of trimethylphosphine (PMe₃), 1,3,4,5-tetramethylimidazolin-2-ylidene (^MeIMe) or carbon monoxide (CO) afforded the complexes [(η⁶-p-cymene){(IDipp)P}M(PMe₃)]BAr^F] ( 4 a , M=Ru; 4 b , M=Os), [(η⁶-p-cymene){(IDipp)P}Os(^MeIMe)]BAr^F] ( 5 ) and [(η⁵-C₅Me₅){(IDipp)P}IrL][BAr^F] ( 6 , L=PMe₃; 7 , L=^MeIMe; 8 , L=CO). These cationic N-heterocyclic carbene-phosphinidene complexes feature very similar structural and spectroscopic properties as prototypic nucleophilic arylphosphinidene complexes such as low-field ³¹P NMR resonances and short metal-phosphorus double bonds. Density functional theory (DFT) calculations reveal that the metal-phosphorus bond can be described in terms of an interaction between a triplet [(IDipp)P]⁺ cation and a triplet metal complex fragment ligand with highly covalent σ- and π-contributions. Crystals of the C−H activated complex 9 were isolated from solutions containing the PMe₃ complex, and its formation can be rationalized by PMe₃ dissociation and formation of a putative 16-electron intermediate [(η⁵-C₅Me₅)Ir{P(IDipp)}I][BAr^F], which undergoes C−H activation at one of the Dipp isopropyl groups and addition along the iridium-phosphorus bond to afford an unusual η³-benzyl coordination mode.     

Deep‐red light‐emitting phosphorescent dendrimer encapsulated tris‐[2‐benzo[b]thiophen‐2‐yl‐pyridyl] iridium (III) core for light‐emitting device applications

New deep‐red light‐emitting phosphorescent dendrimers with hole‐transporting carbazole dendrons were synthesized by reacting tris(2‐benzo[b]thiophen‐2‐yl‐pyridyl) iridium (III) complex with carbazolyl dendrons by DCC‐catalyzed esterification. The resulting first‐, second‐, and third‐generation dendrimers were found to be highly efficient as solution‐processable emitting materials and for use in host‐free electrophosphorescent light‐emitting diodes. We fabricated a host‐free dendrimer EL device with configuration ITO/PEDOT:PSS (40 nm)/dendrimer (55 nm)/BCP (10 nm)/Alq₃ (40 nm)/LiF (1 nm)/Al (100 nm) and characterized the device performance. The multilayered devices showed luminance of 561 cd/m² at 383.4 mA/cm² (12 V) for 15 , 1302 cd/m² at 321.3 mA/cm² (14 V) for 16 , and 422 cd/m² at 94.4 mA/cm² (18 V) for 17 . The third‐generation dendrimer, 17 (η_ext = 6.12% at 7.5 V), showed the highest external quantum efficiency (EQE) with an increase in the density of the light‐harvesting carbazole dendron. Three dendrimers exhibited considerably pure deep‐red emission with CIE 1931 (Commission International de L'Eclairage) chromaticity coordinates of x = 0.70, y = 0.30. The CIE coordinates remained very stable with the current density. The integration of rigid hole‐transporting dendrons and phosphorescent complexes provides a new route to design highly efficient solution‐processable materials for dendrimer light‐emitting diode (DLED) applications. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 7517–7533, 2008     

A rapid method for the spectrophotometric determination of palladium(II) and osmium(VIII)

Propionyl promazine phosphate is proposed as a new reagent for the rapid spectrophotometric determination of microgram amounts of Pd(II) and Os(VII). PPP instantaneously forms an orange-red 1:1 complex with Pd(II) in sodium acetate-hydrochloric acid buffer of pH 0.8 to 4.0 at room temperature. The reagent also forms an orange-red radical cation with Os(VIII) in 0.5 to 2.0 M hydrochloric acid. The Pd-PPP complex exhibits an absorption maximum at 490–500 nm with molar absorptivity of 7.1 × 10³ liter mol^?1 cm^?1. The Os-PPP radical cation has an absorption maximum at 505–515 nm with molar absorptivity of 2.21 × 10⁴ liters mol^?1 cm^?1. The Sandell sensitivity is 0.022 μg/cm² (Pd) and 0.008 μg/ cm² (Os). Beer's law is valid over the concentration range 0.2 to 21 ppm (Pd) and 0.2 to 4.2 ppm (Os). The proposed method offers the advantages of simplicity, rapidity, and without the need for heating or extraction. The reagent is used for the determination of Pd in the synthetic mixtures corresponding to Pd alloys used in jewelery and Os in osmiridium alloy.     

Mirror‐Image Organometallic Osmium Arene Iminopyridine Halido Complexes Exhibit Similar Potent Anticancer Activity

Four chiral Os^II arene anticancer complexes have been isolated by fractional crystallization. The two iodido complexes, (S_Os,S_C)‐[Os(η⁶‐p‐cym)(ImpyMe)I]PF₆ (complex 2 , (S)‐ImpyMe: N‐(2‐pyridylmethylene)‐(S)‐1‐phenylethylamine) and (R_Os,R_C)‐[Os(η⁶‐p‐cym)(ImpyMe)I]PF₆ (complex 4 , (R)‐ImpyMe: N‐(2‐pyridylmethylene)‐(R)‐1‐phenylethylamine), showed higher anticancer activity (lower IC₅₀ values) towards A2780 human ovarian cancer cells than cisplatin and were more active than the two chlorido derivatives, (S_Os,S_C)‐[Os(η⁶‐p‐cym)(ImpyMe)Cl]PF₆, 1 , and (R_Os,R_C)‐[Os(η⁶‐p‐cym)(ImpyMe)Cl]PF₆, 3 . The two iodido complexes were evaluated in the National Cancer Institute 60‐cell‐line screen, by using the COMPARE algorithm. This showed that the two potent iodido complexes, 2 (NSC: D‐758116/1) and 4 (NSC: D‐758118/1), share surprisingly similar cancer cell selectivity patterns with the anti‐microtubule drug, vinblastine sulfate. However, no direct effect on tubulin polymerization was found for 2 and 4 , an observation that appears to indicate a novel mechanism of action. In addition, complexes 2 and 4 demonstrated potential as transfer‐hydrogenation catalysts for imine reduction.     

Isophorone－based Fluorescent Dopant for Red Organic Electrolumi－nescence Device

lsophorone-based red fluorescent compound 3-(dicyanomethy-lene ) -5, 5-dimethyi- 1- [ 2- ( N-ethyl-3-carbazyi ) ethylene ] cyciohe-xene (DCDCC) was synthesized for use in organic Hght-emit-ring diodes (OLEDs). DCDCC was characterized by narrow emission in photoluminescence with full.width at half-maximum of only 50 nm in solution and in thin solid film of 70 nm width. devices with configuration of ITO/NPB/Alq3:DCDCC/Alq3/Mg: Ag were fabricated utilizing DCDCC as dopant emitter. An efficient red emission peaked at 612 nm was obtained for the device with 1% (wt.%) DCDCC in Alq3. The maximum luminance and current efficiency were as high as 3700 cd/m^2 at 14 V and 1.25 cd/A at 150 mA/cm^2, respective-ly.     

High Molar Extinction Coefficient Organic Sensitizers for Efficient Dye‐Sensitized Solar Cells

We have designed and synthesized highly efficient organic sensitizers with a planar thienothiophene–vinylene–thienothiophene linker. Under standard global AM 1.5 solar conditions, the JK‐113 ‐sensitized cell gave a short circuit photocurrent density (J_sc) of 17.61 mA cm^?2, an open‐circuit voltage (V_oc) of 0.71 V, and a fill factor (FF) of 72 %, corresponding to an overall conversion efficiency (η) of 9.1 %. The incident monochromatic photo‐to‐current conversion efficiency (IPCE) of JK‐113 exceeds 80 % over the spectral region from 400 to 640 nm, reaching its maximum of 93 % at 475 nm. The band tails off toward 770 nm, contributing to the broad spectral light harvesting. Solar‐cell devices based on the sensitizer JK‐113 in conjunction with a volatile electrolyte and a solvent‐free ionic liquid electrolyte gave high conversion efficiencies of 9.1 % and 7.9 %, respectively. The JK‐113 ‐based solar cell fabricated using a solvent‐free ionic liquid electrolyte showed excellent stability under light soaking at 60 °C for 1000 h.     

Synthesis and photovoltaic properties of new europium complex Eu（DBM）3（CPyBM）

A new europium（Ⅲ） complex, tris（dibertzoylmethanate）{ 1-[9-hexyl-9-carbazole]-2-（2-pyridyl）-bertzimidazole}europium（Ⅲ） [Eu（DBM）a（CPyBM）] was synthesized and used as an electron-acceptor and electron-transport layer in organic photovoltaic （PV） device. Power conversion efficiency achieved from the device was 1.04% under illumination with 365 nm UV light at 1.6 mW/cm^2. Compared with the previous reported devices based on Eu（Ⅲ） complexes, the PV performances were improved. The working mechanism of the organic PV device was discussed.     

A Series of Dibenzofuran-Based n-Type Exciplex Host Partners Realizing High-Efficiency and Stable Deep-Red Phosphorescent OLEDs

Deep-red to near-infrared (NIR) OLEDs, which yield emission peak wavelengths beyond λ=660 nm, are applicable as unique light sources in plant growth or health monitoring systems. Compared with other visible-spectrum OLEDs, however, research in the field of deep-red OLEDs is not as advanced. In this work, three new types of dibenzofuran-based host materials are developed as n-type exciplex host partners. Combining these with the deep-red iridium complex bis(2,3-diphenylquinoxaline)iridium(dipivaloylmethane) ([(DPQ)₂Ir(dpm)]) and N,N′-di(naphalene-1-yl)-N,N′-diphenylbenzidine (α-NPD) as a p-type exciplex host partner, a highly efficient deep-red OLED can be realized with a maximum external quantum efficiency (η_ext,max) of over 16 % with Comission Internationale de l′Éclairge (CIE) coordinates of (0.71, 0.28). In addition, the effect of the doping concentration and the p/n ratio of the exciplex host on the efficiency and the lifetime of the OLEDs are investigated. Consequently, the optimized device exhibits a η_ext,max of over 15 % and a six-time longer lifetime operating at high brightness of 100 cd m⁻² compared with other state-of-the-art deep-red OLEDs.     

Efficient electroluminescence from new lanthanide (Eu3+, Sm3+) complexes

The syntheses, structures, and electroluminescent properties are described for two new lanthanide complexes Ln(HFNH)3phen [HFNH = 4,4,5,5,6,6,6-heptafluoro-1-(2-naphthyl)hexane-1,3-dione; phen = 1,10-phenanthroline; Ln = Eu3+ (1), Sm3+ (2)]. Both complexes exhibit bright photoluminescence at room temperature (RT) due to the characteristic emission of Eu3+ and Sm3+ ion. Several devices using the two complexes as emitters were fabricated. The performances of these devices are among the best reported for devices using europium complex and samarium complex as emitters. The device based on 1 with the structure ITO/TPD (50 nm)/1:CBP (10%, 40 nm)/BCP (20 nm)/AlQ (30 nm)/LiF (1 nm)/Al (200 nm) exhibits the maximum brightness of 957 cd/m2, current efficiency of 4.14 cd/A, and power efficiency of 2.28 lm/W with a pure red Eu3+ ion emission. Especially, at the high brightness of 200 cd/m2, the device of 1 still has a high current efficiency of 2.15 cd/A. The device of 2 with a three-layer structure of ITO/TPD (50 nm)/2 (50 nm)/BCP (20 nm)/LiF (1 nm)/Al (200 nm) gives the maximum brightness of 42 cd/m2, current efficiency of 0.18 cd/A. By the comparison of the electroluminescent properties of devices based on Eu(TTA3phen (TTA = 2-thenoyltrifluoroacteonate) and 1, we conclude that the polyfluoration on the alkyl group of the ligand and the introduction of the long conjugate naphthyl group into the ligand improve the efficiency of 1-doped devices, especially at high current densities.     

Improvement of the Water Resistance of a Narrow‐Band Red‐Emitting SrLiAl3N4:Eu2+ Phosphor Synthesized under High Isostatic Pressure through Coating with an Organosilica Layer

A SrLiAl₃N₄:Eu²⁺ (SLA) red phosphor prepared through a high‐pressure solid‐state reaction was coated with an organosilica layer with a thickness of 400–600 nm to improve its water resistance. The observed 4f⁶5d→4f⁷ transition bands are thought to result from the existence of Eu²⁺ at two different Sr²⁺ sites. Luminescence spectra at 10 K revealed two zero‐phonon lines at 15377 (for Eu(Sr1)) and 15780 cm^?1 (for Eu(Sr2)). The phosphor exhibited stable red emission under high pressure up to 312 kbar. The configurational coordinate diagram gave a theoretical explanation for the Eu^2+/3+ result. The coated samples showed excellent moisture resistance while retaining an external quantum efficiency (EQE) of 70 % of their initial EQE after aging for 5 days under harsh conditions. White‐light‐emitting diodes of the SLA red phosphor and a commercial Y₃Al₅O₁₂:Ce³⁺ yellow phosphor on a blue InGaN chip showed high color rendition (CRI=89, R9=69) and a low correlated color temperature of 2406 K.     

Migratory-insertion reactions involving the thiocarbonyl ligand. dihapto-thioacyl complexes from the rearrangement of arylthiocarbonyl complexes of osmium(II). Structure of Os(η2-CSR)(η1-O2CCF3)(CO)(PPh3)2

Reaction of HgR₂ with OsHCl(CS)(PPh₃)₃ yields red, five-coordinate, OsRCl-(CS)(PPh₃)₂ (R = p-tolyl). From this have been derived the compounds OsRX(CS)(PPh₃)₂ with X = Br, I, S₂CNEt₂, O₂CMe, O₂CCF₃. These compounds add an additional ligand, MeCN, CO or CNR to form colourless, six coordinate arylthiocarbonyl complexes, which undergo migratory-insertion reactions to form red, dihapto-thioacyl complexes. The crystal structure of a representative example, Os(η²-CSR)(η¹-O₂CCF₃)(CO)PPh₃)₂ has been determined. The red equant crystals are orthorhombic, space group P2₁2₁2₁, a 11.584(1), b 19.184(2), c 18.90(1) Å, V 4199 ų, Z  4. The structure was solved by conventional heavy-atom methods and refined by full-matrix least-squares employing anisotropic thermal parameters for all non-hydrogen atoms except the carbon atoms of the triphenylphosphines. The final R factor is 0.057 for 2868 observed reflections.The coordination geometry in the monomeric complex is that of an octahedron distorted by the constraints of the ligands. The triphenyl phosphine ligands are mutually trans; the equatorial plane contains carbonyl, monohapto-trifluoroacetate, and dihapto-thioacyl ligands. Bond distances and angles are OsP 2.405, 2.407(4) Å; POsP 173.9(1)°; OsCO 1.83(2) Å; Os-O (trifluoroacetate) 2.206(11) Å; OsC (thioacyl) 1.91(2); OsS 2.513(6); CS 1.72 Å. The CS bond length implies a reduction in bond order from 2.0 to approx. 1.5 upon coordination to the metal.The η²-thioacyl ligand in Os(η²-CSR)Cl(CNR)(PPh³)₂ is methylated with methyl triflate and further reaction with LiCl produces the thiocarbene complex OsCl₂(C[SMe]R)(CNR)(PPh₃)₂.     

Speciation Analysis of Osmium(VIII) and Osmium(IV) by UV‐VIS Spectrophotometry Using Quercetin as the Reagent

Abstract

The UV‐VIS spectrophotometric methods for the determination of Os(VIII) (as OsO₄) and Os(IV) (as OsCl₆ ^2? complex) in their mixtures were developed. Quercetin (Q), a flavonoid compound, was used as a chromogenic reagent. Both direct and derivative spectrophotometry can be employed for the determination of Os(VIII). The calculation of the first‐derivative spectrum of the examined mixture and the use of the signal at 285.1 nm allows reaching a better detection limit (0.01 µg mL^?1 Os) as compared with direct spectrophotometry (0.1 µg mL^?1 Os). Relative standard deviations of the results are in the range of 0.87%–4.65% and 0.45%–1.15% for direct and derivative mode, respectively. Selective redox reaction of OsO₄ with Q under the conditions used (0.05 M HCl, 1×10^?4 M Q, 15 min heating at 70°C) makes the basis of its determination in mixtures with the OsCl₆ ^2? complex. Quercetin does not react with the OsCl₆ ^2? complex. The signals of the OsCl₆ ^2? complex can be isolated from the examined mixtures by the calculation of the third‐order derivative spectra and the use of the values at 340.0 nm. The effectiveness of the reduction of OsO₄ in chloride solutions has been studied by the developed method.     

Alkylimido osmium(VI) and ruthenium(VI) porphyrins. Crystal and molecular structures of Os(TTP)(O)(NBut)- EtOH and OS(4-C1-TPP)(NBut)2

Oxo(tert-butylimido) or bis(tert-butylimido)osmium(VI) porphyrins Os(Por)(O)( NBu^t) and Os(Por)(NBu^t)2, [Por=meso-tetrakis(p-tolyl)porphyrinato (TTP) and meso-tetrakis(4-chlorophenyl)porphyrinato (4-CI-TPP)] were synthesized by air oxidation of bis(tert-butylamine)osmium(II) porphyrins [Os(Por)(H₂NBu^t)n (Por=TPP, 4-C1-TPP], depending on whether text-butylamine is present. The bis(tert-butylamine)ruthenium(II) porphyrins [Ru(Por)(H₂NBu^t)z, Por=TTP, 4-CI-TPP] can undergo bromine oxidation to give oxo(tert-butylimido)ruthenium(VI) complexes in quantitative yields. All these nem complexes were characterized by ¹H NMR, UV-Visible and IR spectroscopy. The X-ray crystal structures of Os(TTP)(O)(NBu^t).EtOH and Os(4-Cl-TPP)(NBu^t)₂ have been determined. Crystal data: for Os(TTP)(O)(NBu').EtOH: monoclinic, space group P2₁/c, a=1.3546(6) nm, b=2.3180(3) am, c=1.6817(3) nm, β=90.84(2)°, V=527.97(1) nm³, Z=4. The Os=O and Os=NBu^t distances in Os(TTP)(O)(NBu^t).EtOH are 0.1772(7) nm and 0.1759(9) nm, respectively. The average Os=NBu^t distance of Os(4-C1-TPP)(NBu^t)₂ is 0.1775 nm.     

Simple Synthesis of Red Iridium(III) Complexes with Sulfur-Contained Four-Membered Ancillary Ligands for OLEDs

Phosphorescent iridium(III) complexes have been widely researched for the fabrication of efficient organic light-emitting diodes (OLEDs). In this work, three red Ir(III) complexes named Ir-1, Ir-2, and Ir-3, with Ir-S-C-S four-membered framework rings, were synthesized efficiently at room temperature within 5 min using sulfur-containing ancillary ligands with electron-donating groups of 9,10-dihydro-9,9-dimethylacridine, phenoxazine, and phenothiazine, respectively. Due to the same main ligand of 4-(4-(trifluoromethyl)phenyl)quinazoline, all Ir(III) complexes showed similar photoluminescence emissions at 622, 619, and 622 nm with phosphorescence quantum yields of 35.4%, 50.4%, and 52.8%, respectively. OLEDs employing these complexes as emitters with the structure of ITO (indium tin oxide)/HAT-CN (dipyra-zino[2,3-f,2′,3′-h]quinoxaline-2,3,6,7,10,11-hexacarbonitrile, 5 nm)/TAPC (4,4′-cyclohexylidenebis[N,N-bis-(4-methylphenyl)aniline], 40 nm)/TCTA (4,4″,4″-tris(carbazol-9-yl)triphenylamine, 10 nm)/Ir(III) complex (10 wt%): 2,6DCzPPy (2,6-bis-(3-(carbazol-9-yl)phenyl)pyridine, 10 nm)/TmPyPB (1,3,5-tri(mpyrid-3-yl-phenyl)benzene, 50 nm)/LiF (1 nm)/Al (100 nm) achieved good performance. In particular, the device based on complex Ir-3 with the phenothiazine unit showed the best performance with a maximum brightness of 22,480 cd m⁻², a maximum current efficiency of 23.71 cd A⁻¹, and a maximum external quantum efficiency of 18.1%. The research results suggest the Ir(III) complexes with a four-membered ring Ir-S-C-S backbone provide ideas for the rapid preparation of Ir(III) complexes for OLEDs.     

Synthesis and characterization of a cadmium-dichloro compound of N,N , O -di-2-pyridyl ketone thiophene-2-carboxylic acid hydrazone (η 3-dpktch). The structure of [CdCl2(η 3-dpktch)]

The reaction between dpktch and CdCl₂ in refluxing acetonitrile gave [CdCl₂(η³-dpktch)] in good yield. Spectroscopic measurements divulge the coordination of dpktch and the elemental analysis confirmed its formulation. Optical measurements in N,N-dimethylformamide (dmf) and dimethylsulfoxide (DMSO) in the absence and presence of a proton donor/acceptor disclosed two highly sensitivity interlocked intra-ligand-charge-transfer transitions (ILCT) that are sensitive to their surroundings. Under basic conditions, a low-energy electronic transition with an extinction coefficient of 17,400?±?2000?M^?1cm^?1 appeared at ～403?nm and a peak minimum appeared at 326?nm. Under acidic conditions, a high energy electronic transition with extinction coefficient of 13,500?±?2000?M^?1cm^?1 appeared at ～330?nm and a shoulder appeared at ～400?nm. The addition of an acid to a dmf solution of [CdCl₂(η³-dpktch)] caused the disappearance of the low energy absorption band at 403?nm and a peak maximum appeared at 330?nm. The reverse was observed when a base was added to a DMSO solution of [CdCl₂(η³-dpktch)]. Electrochemical measurements reveal reduction of coordinated CdCl₂ and oxidation of electrodeposited cadmium metal along with ligand-based redox processes. X-ray crystallographic analysis on a monoclinic, P2₁/n single crystal of [CdCl₂(η³-dpktch)], confirmed the N,N,O-coordination of dpktch and revealed digitated units of [CdCl₂(η³-dpktch)] interlocked via a web of hydrogen bonds.     

Saturated Red‐Emitting Electrophosphorescent Polymers with Iridium Coordinating to β‐Diketonate Units in the Main Chain

Summary: A series of novel copolymers with fluorene‐alt‐carbazole segments and β‐diketonate moieties coordinating to iridium were synthesized by Suzuki polycondensation, and characterized by ¹H NMR, ¹³C NMR, and GPC. In the absorption spectra of the copolymers, metal‐to‐ligand charge‐transfer transitions coming from iridium complex increased in intensity with increasing content of Ir complex in copolymers. The photoluminescence spectra of the copolymers were dominated by emission from the iridium complex with peak at ca. 620 nm even at the feed ratio of the complex as low as 0.5 mol‐%. The electrochemical investigation indicated that the incorporation of carbazole and iridium complex units reduce the barrier for both hole and electron injection compared with the polyfluorene. The light‐emitting diodes using the copolymers as emission layer under different device configurations were fabricated. The devices with 2‐(4‐biphenylyl)‐5‐(4‐tert‐butylphenyl)‐1,3,4‐oxadiazole (PBD) show significantly higher external quantum efficiencies than those without PBD. A saturated red‐emitting polymer light‐emitting diode with emission peak at 628 nm, the maximum external quantum efficiency of 0.6% at the current density (J) of 38.5 mA · cm⁻², and the maximum luminance of 541 cd · m⁻² at 15.8 V was achieved from the device ITO/PEDOT/PFCzIrpiq3 + PBD (40%)/Ba/Al.

Novel copolymers with fluorene‐alt‐carbazole segments and iridium coordinating to β‐diketonate in the main chain.