Vladimir Grushin

Highly efficient electroluminescent materials based on fluorinated organometallic iridium compounds

We report a class of highly efficient electroluminescent materials based on fluorinated iridium compounds. Using aluminum as the cathode, a device, using fac-tris[5-fluoro-2(5-trifluoromethyl-2-pyridinyl)phenyl-C,N]iridium (Ir-2h) as the luminescent layer, displayed intense electroluminescence at 525 nm with an efficiency of 20 cd/A and a maximum radiance of 4800 cd/m2. Differing from the previously reported Ir(ppy)3, Ir-2h can be used in the undiluted form without the use of a charge-transporting host. This indicates that Ir-2h by itself has good enough charge-transporting properties. Photoluminescence studies at room temperature and 77 K revealed that electroluminescence originates from the metal-to-ligand charge transfer state with a quantum yield of 0.56 for Ir-2h and 0.5 for Ir(ppy)3 in toluene at room temperature. In the thin-film form, photoluminescence quantum yield of Ir-2h is a factor of 10 greater than that of Ir(ppy)3 due to the larger self-quenching effect of Ir(ppy)3.

Synthesis of 2,5‐Diformylfuran and Furan‐2,5‐Dicarboxylic Acid by Catalytic Air‐Oxidation of 5‐Hydroxymethylfurfural. Unexpectedly Selective Aerobic Oxidation of Benzyl Alcohol to Benzaldehyde with Metal=Bromide Catalysts

The alcohol group of hydroxymethylfurfural (compound 1, HMF) is preferentially oxidized by dioxygen and metal/bromide catalysts [Co/Mn/Br, Co/Mn/Zr/Br; Co/Mn=Br/(Co+Mn) = 1.0 mol/mol] to form the dialdehyde, 2,5-diformylfuran (compound 2, DFF) in 57% isolated yield. HMF can be also oxidized, via a network of identified intermediates, to the highly insoluble 2,5-furandicarboxylic acid (compound 5, FDA) in 60% yield. For comparison, benzyl alcohol gives benzaldehyde in 80% using the same catalyst system. Over-oxidation (to CO2) of HMF is much higher than that of the benzyl alcohol but can be greatly reduced by increasing catalyst concentration.

Palladium Fluoride Complexes: One More Step toward Metal‐Mediated C−F Bond Formation

The first molecular complexes of palladium containing a Pd-F bond, both fluorides and bifluorides, were synthesized and fully characterized in the solid state and in solution. Reactivity studies of the Pd fluoride complexes revealed their unexpected stability and unusual chemical properties, different from the hydroxo, chloro, bromo, and iodo analogues. A novel efficient method to generate naked fluoride was developed using [(Ph(3)P)(2)Pd(F)Ph]. The naked fluoride from the Pd source fluorinated dichloromethane, deprotonated chloroform, and catalyzed di- and trimerization of hexafluoropropene under uncommonly mild conditions.

Cyclic diaryliodonium ions: old mysteries solved andnew applications envisaged

For a long time the unusually poor reactivity of cyclic ndiaryliodonium ions toward nucleophiles remained a mystery. Only very nrecently has a solution to this puzzle been found, shedding light on the nmechanism of aromatic nucleophilic substitution reactions of iodonium nsalts. This article provides an overview of the most important current nadvances in the field, both theoretical and practical.

New, efficient electroluminescent materials based onorganometallic Ir complexes

Reaction of IrCl3 with fluorinated 2-arylpyridines nin the presence of AgO2CCF3 affords nfac-tris-cyclometalated arylpyridine Ir complexes exhibiting nexcellent processing and electroluminescent properties which can be nfine-tuned via systematic control of the nature and position of nthe substituents on the aromatic rings.

Facile preparation and synthetic applications of LiCH2C(CF3)2OLi

Abstract Bromohydrin BrCH 2 C(CF 3 ) 2 OH readily reacts with two equivalents of n -BuLi at −78xa0°C to produce the corresponding dilithium derivative LiCH 2 C(CF 3 ) 2 OLi in high yield. This dilithiated derivative reacts selectively, acting as a C-nucleophile, with a variety of electrophiles such as R 2 PCl, carbonyl compounds, and epoxides, to give electron-deficient phosphines R 2 PCH 2 C(CF 3 ) 2 OH, 1,3- and 1,4-diols, correspondingly.

Electrophilic Stannylation of Arenes: A New SEAr Reaction

Electrophilic “trifluoroacetatotin(IV)” has been prepared by reaction of tin oxide with trifluoroperacetic acid/trifluoroacetic anhydride, and by reaction of tetraphenyltin with excess trifluoroacetic acid. The electrophilic tin(IV) material prepared by either route reacts reversibly with arenes to make aryl-tin compounds and trifluoroacetic acid. The compounds (C6H5)2Sn4O2(CF3COO)10 and (xylyl)2Sn4O2(CF3COO)10 have been obtained from the reactions with benzene and p-xylene, respectively, and their molecular structures determined by X-ray crystallography. Tin now joins Pb, Tl, and Hg in the list of main group metals whose trifluoroacetato complexes can metalate arenes by C−H activation.