A new series of luminescent platinum(II) azolate complexes with a formula of [Pt(NwedgeN)(2)], in which NwedgeN = mppz (1), bppz (2a), bzpz (2b), bmpz (2c), bqpz (2d), fppz (3a), hppz (3b), bptz (4), hptz (5), were synthesized, and their photophyscial properties were examined. Single-crystal X-ray diffraction studies of 2c and 3b revealed a planar molecular geometry, in which the NwedgeN chelates adopt a trans configuration and show notable interligand C-H...N hydrogen bonding within the complex. Interesting intermolecular interactions were observed in the solid state. Complex 2c formed a slipped-stack structure with a Pt...Pt separation distance of 6.432 Angstroms, while complex 3b showed a columnar stacking with the molecules oriented in an alternating order in relation to the chain axis, giving a much reduced Pt...Pt distance of 3.442 Angstroms. The lowest absorption band for all complexes revealed strong state mixings between the singlet and triplet (MLCT and intraligand pipi) manifolds. Complexes 1 and 2 showed mixed (3)MLCT and (3)pipi phosphorescence in fluid solution. While radiationless deactivation was apparently dominant for complexes 3-5 in solution, resulting in rather weak emission, strong phosphorescence was observed in the room-temperature solid state with the peak wavelength being significantly red shifted compared to that in solution. The emission nature has been tentatively assigned to be (3)MMLCT in character. OLED devices with a multilayer configuration of ITO/NPB/CBP:2a/BCP/Alq(3)/LiF/Al were successfully fabricated using a CBP layer doped with various amount of 2a, ranging from 6 to 100%, as the emitting layer. A substantial red shift with increasing doping concentrations was observed in electroluminescence. With a neat film of 2a, the device showed a green emission with lambda(max) at 556 nm and an external QE of approximately 1.6% at a driving current of 20 mA. Similarly, for the device using a neat film of 3a, an electroluminescence centered at 616 nm with a slightly reduced external QE of approximately 2.1% was recorded. Aggregation of platinum(II) complexes in the solid state was proposed to account for the large red-shift in electroluminescence.

A new indolo[3,2-b]quinoline alkaloid glycoside, jusbetonin (1), and three known alkaloids, namely, 10H-quindoline (2), 6H-quinindoline (3), and 5H,6H-quinindolin-11-one (4), have been isolated from the leaves of Justicia betonica. The structure of 1 was established on the basis of 1D and 2D NMR ((1)H-(1)H COSY, HMQC, and HMBC) and HRFABMS data. Compound 1 is the first example of a glycosylated indolo[3,2-b]quinoline alkaloid, while compound 4 was isolated for the first time from a natural source.

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New Pt(II) dichloride complexes [Pt(1-iqdzH)Cl2] (2a) and [Pt(3-iqdzH)Cl2] (2b), in which idqzH = 1- or 3-isoquinolinyl indazole, were prepared by treatment of the corresponding indazoles with K2PtCl4 in aqueous HCl solution. Despite their nonemissive nature, these complexes could react with excess indazole, sodium picolinate, and 3-trifluoromethyl-5-(2-pyridyl) pyrazole [(fppz)H] to afford the respective a and b series of luminescent complexes [Pt(1-iqdz)(L/\X)] and [Pt(3-iqdz)(L/\X)], where L/\X = 1-iqdz (1a), 3-iqdz (1b), pic (3a, 3b), and fppz (4a, 4b). Single-crystal X-ray diffraction studies of 1b, 2a, and 3b revealed a planar molecular geometry without notable intermolecular Pt...Pt contact in the solid crystal, a result of the steric repulsion imposed by the bulky indazole fragments. For coordination complexes 1, 3, and 4, photoluminescence in degassed CH2Cl2 revealed high quantum efficiency and short radiative lifetimes in the range of several microseconds. As supported by the spectral feature, the associated radiation lifetimes, and a computational approach based on time-dependent density function theory (TD-DFT), the origin of the emission is attributed to a mixed 3MLCT/3pipi transition. The TD-DFT approach further confirmed that, except for the series 1 complexes, the HOMO of 3-iqdz complexes 3b and 4b is much less located at the central Pt(II) atom than the HOMO orbitals of the respective 1-iqdz complexes 3a and 4a, leading to a smaller degree of MLCT contribution. Consequently, there are a blue-shifted emission signal and an inferior emission quantum yield for the 3-iqdz derivatives. OLED devices with a multilayer configuration of ITO/NPB/CBP:3a/BCP/Alq3/LiF/Al were fabricated using a CBP layer doped with various concentrations of 3a, ranging from 6% to 100%, within the emitting layer. The best device performance was realized using a 6% doping concentration, for which the external quantum yield of 4.93%, luminous efficiency of 12.19 cd/A, and power efficiency of 6.12 lm W-1 were observed at 20 mA/cm2, while a maximum luminescence as high as 20296 cd/m2 was also realized at 16 V, showing good prospect for the fabrication of Pt(II) based OLEDs.

The rational design and syntheses of Pt(iqdz)2 (1) and Pt(pydz)2 (2) bearing isoquinolinyl indazole (iqdz)H or pyridyl indazole (pydz)H groups on the coordinating ligands are reported. Single‐crystal X‐ray diffraction studies of 1 reveal a square planar geometry, in which two iqdz ligands adopt a trans‐configuration. Short N…H contacts (∼2.21 Å) are detected between the ortho‐hydrogen atom of isoquinoline and the adjacent N atom of the indazole fragment, making the overall molecular geometry analogous to that of the platinum(II) porphyrinato complexes. The lowest absorption bands for both complexes reveal strong state mixings between singlet and triplet (metal‐to‐ligand charge transfer and intra‐ligand) manifolds. This, in combination with the introduction of a camphor‐like structure to avoid the stacking effect, leads to phosphorescence with unprecedented brightness both in solution and in the solid state. Organic light‐emitting diode (OLED) devices fabricated using 1 as a dopant emitter have been achieved in a multilayer configuration. The results constitute the first highly efficient PtII‐based red OLED.

Cyclohexylidenebishydroperoxide was successfully used as the oxygen source for the oxidation of alpha,beta-Unsaturated ketones for the first time. The corresponding epoxides were obtained in excellent yields under the Weitz-Scheffer reaction conditions.

ABSTRACT

Highly efficient red-emitting electrophosphorescent devices were fabricated by doping an iridium ͑Ir͒ complex containing trifluoromethyl ͑CF 3 ͒-substituted pyrimidine ligand into a conjugated bipolar polyfluorene with triphenylamine and oxadiazole as side chains. The device efficiency can be enhanced through effective exciton confinement using a layer of 1,3,5-tris(Nphenylbenzimidazol-2-yl)benzene on the cathode side and a layer of in situ polymerized tetraphenyldiamine-perfluorocyclobutane on the anode side. For a blend with 5 wt % of the Ir complex, a maximum external quantum efficiency of 7.9 photon/electron % and a maximum brightness of 15800 cd/ m 2 are reached with Commission Internationale de L'Eclairage chromaticity coordinates of x = 0.65 and y = 0.34.