High stability and luminance efficiency thieno[2,3-d]pyridazine-based iridium complexes and their applications in high-performance yellow OLEDs.

Three novel phosphorescent iridium(iii) complexes with thieno[2,3-d]pyridazine derivatives as cyclometalating chelates were successfully synthesized. These complexes exhibited intense green or yellow phosphorescence emission with short lifetimes of 1.71-1.91 µs and very high quantum yields of over 85% in PMMA films. Even in air-equilibrated CH2Cl2, their quantum yields could be up to 36%. They also showed good thermal stability with Td > 338 °C. The electronic structure information of these complexes was discussed by density functional theory. The tris-cyclometalated complex Ir1 was an excellent yellow phosphorescent dopant for OLED applications, and the maximum CE and PE based on it were 58.5 cd A-1 and 45.9 lm W-1, respectively, with the maximum EQE of 18.2% which was ca. 1.4 times more efficient than that of PO-01. These results indicate that these new complexes have potential applications as efficient phosphors in OLEDs.

Interaction and selectivity of 14-crown-4 derivatives with Li+, Na+, and Mg2+ metal ions.

The interactions between crown ether ligands (14-crown-4, 14C4; 4,4,5,5-tetramethylbenzo-14-crown-4, BC4H12-14C4; 4,4,5,5,9,9,10,10-octamethyl-14-crown-4, C8H24-14C4; dibenzo-14-crown ether-4, DB14C4) and alkaline and alkaline earth metal ions (Li+, Na+, Mg2+) were investigated using density functional theory modeling at the M062X/def2SVP and def2TZVP level. The condensed softness analysis of crown ethers, a condensed Fukui function, a condensed dual descriptor, and frontier molecular orbital theory were used to analyze the reactivities of the complexes. The complex stability was analyzed in terms of the binding energies, standard Gibbs free energy of formation, and energy decomposition of the interaction in aqueous solution. The results show that the active sites were mainly located at the carbon atoms of the benzene ring and oxygen atoms. The reactivities of DB14C4 and BC4H12-14C4 are higher than those of 14C4 and C8H24-14C4. The electrostatic interaction is the principal factor determining the stability of the complexes. The complexes containing Li+ has the greatest stability in aqueous solution among the complexes containing Li+, Na+, and Mg2+. BC4H12-14C4 shows selective adsorption toward Li+ in a mixed solution of Li+, Na+, and Mg2+. To evaluate the stability of complexes containing Mg2+, the solvent effect must be accurately described. An energy decomposition analysis was used to evaluate the stability of complexes containing Li+, Na+, and Mg2+, and the solvent effects were considered.

Novel phosphorescent triptycene-based Ir(iii) complexes for organic light-emitting diodes.

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.

High efficiency green OLEDs based on homoleptic iridium complexes with steric phenylpyridazine ligands.

A series of steric phenylpyridazine based homoleptic iridium(iii) complexes (1-3) have been synthesized with novel one-pot methods. Single X-ray structural analyses are conducted on complexes 1 and 2 to reveal their coordination arrangement. These complexes exhibit a very strong green phosphorescence emission with high quantum yields of over 64%. The relationship between photophysical properties and the substituent nature of the complexes is discussed by density functional theory (DFT) and time-dependent DFT. Self-quenching is significantly reduced for these complexes in solid even at very high concentrations because the sterically hindered bicyclo [2.2.2] oct-2-ene and m-substituted CF3 spacers in the phosphor molecules lead to minimum bimolecular interactions. Accordingly, the electroluminescence device based on complex 3 exhibits a maximum luminous efficiency of 64.1 cd A-1 with a high EQE of 25.2% at a high doping concentration of 15 wt%. Meanwhile, when neat 3 was adopted as the emitting layer, the non-doped green device gives a state-of-the-art EQE as high as 15.2% (40.1 cd A-1) along with CIE coordinates of (0.346, 0.599).

Bis-Tridentate Ir(III) Complexes with Nearly Unitary RGB Phosphorescence and Organic Light-Emitting Diodes with External Quantum Efficiency Exceeding 31%.

A new class of neutral bis-tridentate Ir(III) metal complexes that show nearly unitary red, green, and blue emissions in solution is prepared and employed for the fabrication of both monochrome and white-emitting organic light-emitting diodes, among which a green device gives external quantum efficiency exceeding 31%.

Luminescent Pt(II) complexes bearing dual isoquinolinyl pyrazolates: fundamentals and applications.

A series of four Pt(II) metal complexes with trans-arranged isoquinolinyl azolates have been prepared, [Pt(Lx)2], x = 1-4, (1-4). The associated chelates possess various substituents; namely: one t-butyl (Bu(t)) at the 6-position (L1), two Bu(t) groups at the 5,7-positions (L2), one dip (2,6-di-isopropylphenyl) group at the 6-position (L3), and a single dip group at the 4-position of the 1-isoquinolinyl fragment (L4), respectively. Crystal structures of 1 and 4 were determined to shed light on the relationship of photophysics and packing arrangements. Their photophysical properties were measured and compared, for which the solid-state emission spectra of 2 and 4 are nearly identical to the solution spectra of all the Pt(II) complexes, showing the formation of isolated molecular entities. In contrast, the Pt(II) complexes 1 and 3 are found to be sensitive to their morphological states and external stimulus. This is confirmed by the gradual red-shifting of the emission with increasing concentration in the PMMA matrix, and the eventual formation of the broadened, metal-metal-to-ligand charge transfer (MMLCT) emission, by (i) wetting with acetone and drying in air, or (ii) grinding with a mortar and pestle, respectively. Organic light-emitting diodes (OLEDs) were also fabricated using multiple layered architecture and lowered doping concentration (e.g. 8 wt%), the latter is for avoiding dopant aggregation in the emitting layer. The associated OLED performances (i.e. η(max) = 11.5%, 8.5%, and 11.2% for 1, 2 and 3) confirmed their suitability and potential as dopants for phosphorescent OLEDs.

Multi-functional fluorescent probe for Hg2+, Cu2+ and ClO- based on a pyrimidin-4-yl phenothiazine derivative.

A multi-functional fluorescent probe based on PzDPM (10-ethyl-3,7-di(pyrimidin-4-yl)-10H-phenothiazine) for Hg(2+), Cu(2+) and ClO(-) has been synthesized and characterized. The probe comprises an electron-donating fluorophore core of 10-ethylphenothiazine and two Hg(2+)-specific chelating arms of pyrimidin-4-yl. The 10-ethylphenothiazine also acts as a Cu(2+)/ClO(-)-specific reactive moiety. PzDPM exhibits green fluorescence and selectively senses Hg(2+)/Cu(2+) upon coordination/reaction in acetonitrile (MeCN), and behaves as a turn-off chemosensor or ratiometric chemodosimeter, respectively. On the other hand, PzDPM is very weakly emissive in aqueous solution but acts as an excellent turn-on chemodosimeter for ClO(-) in 1 : 4 (v/v) MeCN : Tris-HCl (10 mM, pH = 7.0) with a maximum fluorescent intensity increase of over 110-fold. The probe PzDPM allows the determination of Hg(2+), Cu(2+) and ClO(-) at 10(-7) M levels with satisfactory selectivity.

The effects of different solvents and excitation wavelength on the photophysical properties of two novel Ir(III) complexes based on phenylcinnoline ligand.

Two novel cyclometalated iridium(III) complexes, Ir(pcl)2(pic) and Ir(pcl)2(fpic) (pcl: 3-phenylcinnoline, pic: picolinic acid, fpic: 5-fluoro-2-picolinic acid) were synthesized and characterized by FTIR, (1)H NMR spectroscopy, UV-vis, PL, and MALDI-TOF. These two Ir-complexes geometry were predicted using the Sparkle/PM6 model and suggested to a chemical environment of very low symmetry around the Ir ions (C 1). The PL spectrum of Ir(pcl)2(pic) and Ir(pcl)2(fpic) indicated that these complex belonged to red light emission, and maximum emission wavelength located at 647 and 641 nm, respectively. Most importantly, the effects of different solvents on their photoluminescent properties were detailed investigated. The results indicated that the polarity of solvent played an important role for their emission spectra. With introducing fluoro group to the pyridyl ring, the maximum emission wavelength of Ir(pcl)2(fpic) was blue shifted about 6 nm, and the quantum yield was slightly higher than that of Ir(pcl)2(pic). In addition, the thermal properties of these two Ir-complexes were measured by TGA, and results indicated that they had relative good thermal properties.

Effect of pH on the photophysical properties of two new carboxylic-substituted iridium(III) complexes.

Two cyclometalated iridium(III) complexes have been prepared based on 2-(4-diphenylamino-phenyl)-quinoline and incorporating carboxylic acid ethyl ester (­COOC(2)H(5), (TPAQCE)(2)Irpic and carboxylic acid (­COOH, (TPAQCOOH)(2)Irpic) substituents at the 4-position of the quinoline ligand, respectively. The absorption, emission and (1)H NMR spectra of (TPAQCE)(2)Irpic and (TPAQCOOH)(2)Irpic under alkaline or acidic conditions demonstrate that they respond to the pH of the surrounding solvent environment. The deprotonation of the carboxylic acid group significantly blue-shifts the metal-to-ligand charge transfer absorption band of (TPAQCOOH)(2)Irpic by 48 nm and enhances the emission quantum-yield in DMSO. In addition, (1)H-NMR titration reveals that (TPAQCOOH)(2)Irpic is deprotonated into negatively charged (TPAQCOO(−))(2)Irpic in free DMSO-d(6) solution, and the acid-induced N^O ancillary ligands cleavage or replacement in (TPAQCOOH)(2)Irpic could be ignored. A water-soluble near-neutral optical pH probe (TPAQCOOH)(2)Irpic with pK(a) of ~7 is also reported. In aqueous buffer, (TPAQCOOH)(2)Irpic possesses an obvious emission response with an excellent linearity in the pH range of 6.50­8.00, showing a promising application in bioprocessing.

Phosphorescent chemosensor for Hg2+ and acetonitrile based on iridium(III) complex.

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.

2-[(8-Meth-oxy-carbonyl-4b,8-dimethyl-4b,5,6,7,8,8a,9,10-octa-hydro-phenan-thren-3-yl)amino]-3,5-dinitro-benzoic acid ethyl acetate monosolvate.

The title compound, C(25)H(27)N(3)O(8)·C(4)H(8)O(2), has a diterpene skeleton in which the fused cyclo-hexane rings exhibit chair and half-chair conformations. An intra-molecular C-H⋯O hydrogen bond occurs. In the crystal, N-H⋯O, O-H⋯O and C-H⋯O hydrogen bonds are observed.

1-(2,6-Diisopropyl-phen-oxy)-4-phenyl-phthalazine.

In the title mol-ecule, C(26)H(26)N(2)O, the phenyl and phen-oxy rings form dihedral angles of 54.66 (7) and 84.83 (6)°, respectively, with the phthalazine mean plane. The crystal packing exhibits weak C-H⋯π inter-actions.

Chemiluminescence determination of sulphite using a cyclometalated iridium complex as chemiluminescence reagent.

A simple, fast and accurate chemiluminescence (CL) method for the determination of sulphite has been developed, based on its sensitizing effect on the CL reaction between a novel water-soluble iridium complex, [(dpci)2Ir(bvbbi)](PF6) (dpci = 3,4-diphenylcinnoline; bvbbi = N,N'-bivinylester-(1)H,(1')H-[2,2'] bibenzimidazole) and cerium(IV). Under the optimal experimental conditions, the increased CL response was linear, with the concentration of sulphite over the range 5.0 × 10(-7)-5.0 × 10(-4) mol/L. The detection limit of the method was 1.6 × 10(-7) mol/L, with a relative standard deviation (RSD) of 2.7% for nine repetitive determination of 1.0 × 10(-4) mol/L sulphite. The method was successfully applied to the quantitative analysis of sulphite in sugar samples. The possible reaction mechanism of sulphite on the [(dpci)2Ir(bvbbi)](PF6)-cerium(IV) system is also briefly discussed.

Application of a new iridium complex as a chemiluminescence reagent for the determination of tryptophan.

It was found that a novel iridium complex, [(dpci)(2)Ir(bvbbi)](PF(6)) (dpci = 3,4-diphenylcinnoline, bvbbi = N,N'-bivinyester-(1)H,(1)'H-[2,2'] bibenzimidazole), with Ce(IV) in the presence of sodium sulfite can induce a great chemiluminescence (CL) emission. More importantly, a rapid and sensitive CL method for the determination of tryptophan coupled with a flow-injection analysis (FIA) technique has been developed based on the inhibition effect of the tryptophan to the CL emission of [(dpci)(2)Ir(bvbbi)](PF(6))-Ce(IV)-SO(3)(2-) system. Under the optimum conditions, the decreased CL intensity is proportional with the concentration of tryptophan in the range of 5.0 × 10(-7) to 2.0 × 10(-5) mol L(-1), and the detection limit is 8.2 × 10(-8) mol L(-1) (3σ). The relative standard deviation (RSD) for 11 parallel measurements of 1.0 × 10(-5) mol L(-1) tryptophan is 2.7%. The proposed method has been applied successfully for the determination of tryptophan in its pharmaceutical formulations. Moreover, the possible inhibition mechanism of tryptophan on [(dpci)(2)Ir(bvbbi)](PF(6))-Ce(IV)-SO(3)(2-) CL system was briefly discussed.

(4'-All-yloxy-2,2':6',2''-terpyridine)(dibenzoyl-methanido)dinitratoerbium(III) acetonitrile solvate.

The title complex, [Er(C(15)H(11)O(2))(NO(3))(2)(C(18)H(15)N(3)O)]·CH(3)CN, has been synthesized from 4'-all-yloxy-2,2':6',2''-terpyridine (altpy), dibenzoyl-methane and erbium nitrate. The distorted monocapped square anti-prismatic coordination polyhedron is formed by a bidentate dibenzoyl-methanide residue, a tridentate altpy ligand and two nitrate anions that act as bidentate ligands and occupy mutually trans sites.

(4'-All-yloxy-2,2':6',2''-terpyridine-κN,N',N'')(dibenzoyl-methanido-κO,O')bis-(nitrato-κO,O')neodymium(III) acetonitrile solvate.

The title complex, [Nd(C(15)H(11)O(2))(NO(3))(2)(C(18)H(15)N(3)O)]·CH(3)CN or [Nd(altpy)(dbm)(NO(3))(2)]·CH(3)CN (altpy = 4'-all-yl-oxy-2,2':6',2''-terpyridine, dbm = dibenzoyl-methanide anion), has been synthesized from 4'-all-yloxy-2,2':6',2''-terpyridine, dibenzoyl-methanate and neodymium nitrate. The Nd(3+) atom is nine-coordinated by two O atoms from the bidentate dbm ligand, three N atoms from the tridentate altpy ligand and four O atoms from two nitrate anions that act as bidentate ligands and occupy mutually trans sites in a distorted monocapped square-anti-prismatic geometry.

Optimization of holographic storage with modulated recording beams in a thick polyvinyl alcohol/acrylamide photopolymer.

In a holographic photopolymer system, the storage properties were often limited due to the attenuation in depth of light during the recording step. To obtain smaller values of the depth attenuation profiles in 1 mm thick polyvinyl alcohol/acrylamide (PVA/acrylamide) photopolymers, we used a triangle prism, sitting one face tilted at 13.7 degrees to the axis within the focus of a lens, to modulate the distribution of recording beams. Doing this permitted larger refractive index modulation depth to be achieved, and larger dynamic range (M#=9.2) was obtained in the PVA/acrylamide photopolymers.

Near-infrared luminescent lanthanide (Er, Nd) complexes covalently bonded to a terpyridine-functionalized silica matrix.

New kinds of hybrid materials containing covalently bonded tris(dibenzoylmethanate)Ln complexes (Ln=Er, Nd) in a terpyridine-functionalized silica matrix have been prepared and their near-infrared luminescence properties reported.