Oxybis(dimesitylborane) dichloro­methane hemisolvate

The title compound, C36H44B2O·0.5CH2Cl2, contains an almost linear O—B—O linkage [177.23 (15)°] and approximately orthogonal [interplanar angles 89.49 (5) and 80.77 (4)°] trigonal planar B centers, consistent with the previously reported non-solvated structure [Cardinet al. (1983). J. Chem. Res. (S), p. 93]. Inter­molecular C—H⋯π inter­actions exist between mesityl groups, with a C—H⋯centroid separation of 3.6535 (18) Å. The dichloromethane mol­ecules lie on twofold rotation axes

Bis(μ-dimesitylborinato-κ2 O:O)bis­[(2-methyl­pyridine-κN)lithium]

The title compound, [Li2(C18H22BO)2(C6H7N)2], is a lithium dimesitylboroxide dimer in which the lithium cation is also coordinated by one mol­ecule of 2-methyl­pyridine. At the core of the structure is an Li2O2 four-membered ring. The structure is centrosymmetric with an inversion centre midway between two Li atoms. Inter­molecular C—H⋯π inter­actions and π–π inter­actions between the 2-methyl­pyridine rings exist [centroid–centroid distance = 3.6312 (16) Å]

Diffusion doping of cobalt in rod-shape anatase TiO\u3csub\u3e2\u3c/sub\u3e nanocrystals leads to antiferromagnetism†

Cobalt(II) ions were adsorbed to the surface of rod-shape anatase TiO2 nanocrystals and subsequently heated to promote ion diffusion into the nanocrystal. After removal of any remaining surface bound cobalt, a sample consisting of strictly cobalt-doped TiO2 was obtained and characterized with powder Xray diffraction, transmission electron microscopy, UV-visible spectroscopy, fluorescence spectroscopy, X-ray photoelectron spectroscopy, SQUID magnetometry, and inductively-coupled plasma atomic emission spectroscopy. The nanocrystal morphology was unchanged in the process and no new crystal phases were detected. The concentration of cobalt in the doped samples linearly correlates with the initial loading of cobalt(II) ions on the nanocrystal surface. Thin films of the cobalt doped TiO2 nanocrystals were prepared on indium-tin oxide coated glass substrate, and the electrical conductivity increased with the concentration of doped cobalt. Magnetic measurements of the cobalt-doped TiO2 nanocrystals reveal paramagnetic behavior at room temperature, and antiferromagnetic interactions between Co ions at low temperatures. Antiferromagnetism is atypical for cobalt-doped TiO2 nanocrystals, and is proposed to arise from interstitial doping that may be favored by the diffusional doping mechanism

8-Iodoquinolinium triiodide tetrahydrofuran solvate

The title compound, C9H7IN+·I3−·C4H8O, was synthesized from 8-aminoquinoline using the Sandmeyer reaction. The 8-iodoquinolinium cation is essentially planar and the triiodide ion is almost linear. N—H...O hydrogen bonds, and intermolecular I...I [3.7100 (5) Å] and I...H interactions, between the cation, anion and solvent molecules result in the formation of sheets oriented parallel to the (overline{1}03) plane. Between the sheets, 8-iodoquinolinium and triiodide ions are stacked alternately, with I...C distances in the range ∼3.8–4.0 Å

Direct arylation catalysis with chloro[8-(dimesitylboryl)quinoline-κN]copper(I)

We report direct arylation of arylhalides with unactivated sp2 C–H bonds in benzene and naphthalene using a copper(I) catalyst featuring an ambiphilic ligand, (quinolin-8-yl)dimesitylborane. Direct arylation could be achieved with 0.2 mol % catalyst and 3 equivalents of base (KO(t-Bu)) at 80 °C to afford TON ≈160–190 over 40 hours

Chloro({2-[mesityl(quinolin-8-yl-κN)boryl]-3,5-dimethyl-phenyl}methyl-κC)palladium(II) as a Catalyst for Heck Reactions

We recently reported an air and moisture stable 16-electron borapalladacycle formed upon combination of 8-quinolyldimesitylborane with bis(benzonitrile)dichloropalladium(II). The complex features a tucked mesityl group formed upon metalation of an ortho-methyl group on a mesityl; however it is unusually stable due to contribution of the boron pz orbital in delocalizing the carbanion that gives rise to an η4-boratabutadiene fragment coordinated to Pd(II), as evidenced from crystallographic data. This complex was observed to be a highly active catalyst for the Heck reaction. Data of the catalyst activity are presented alongside data found in the literature, and initial comparison reveals that the borapalladacycle is quite active. The observed catalysis suggests the borapalladacycle readily undergoes reductive elimination; however the Pd(0) complex has not yet been isolated. Nevertheless, the ambiphilic ligand 8-quinolyldimesitylborane may be able to support palladium in different redox states

Spectroscopic Characterization of Highly Dispersed Vanadia Supported on SBA-15

Spectroscopic analysis was used to gain new insight into the molecular structures occurring during the synthesis of highly dispersed silica SBA-15 supported vanadia (VOx/SBA-15). VOx/SBA-15 was prepared by a grafting/anion-exchange procedure. As a first step of the procedure, the inner pores of SBA-15 are functionalized via grafting of 3-aminopropyltrimethoxysilane. After formation of the corresponding ammonium salt, decavanadate (V10O286-) is incorporated into the pores by anion exchange. In the final step, calcination of the decavanadate precursor yields the chemically bonded vanadia species. Using this approach, vanadium loadings of up to 22 wt % V on SBA-15 were obtained. As followed by Raman spectroscopy, upon dehydration, the structure of the supported vanadia changes dramatically. Raman and diffuse reflectance UV-VIS spectroscopy under dehydrated conditions reveal the presence of different vanadia structures (monomers, polymers and crystals) as a function of vanadium loading (0 – 22 wt % V). The maximum coverage of vanadia species on SBA-15 is achieved at ~7.2 wt % V (2.3 V/nm2). At loadings up to 7.2 wt % V, the vanadia species are mainly present as isolated tetrahedral species, whereas at higher loadings V2O5 crystallites are formed, in addition to monomeric and polymeric vanadia species

Spectroscopic Characterization of Highly Dispersed Vanadia Supported on SBA-15

Spectroscopic analysis was used to gain new insight into the molecular structures occurring during the synthesis of highly dispersed silica SBA-15 supported vanadia (VOx/SBA-15). VOx/SBA-15 was prepared by a grafting/anion-exchange procedure. As a first step of the procedure, the inner pores of SBA-15 are functionalized via grafting of 3-aminopropyltrimethoxysilane. After formation of the corresponding ammonium salt, decavanadate (V10O286-) is incorporated into the pores by anion exchange. In the final step, calcination of the decavanadate precursor yields the chemically bonded vanadia species. Using this approach, vanadium loadings of up to 22 wt % V on SBA-15 were obtained. As followed by Raman spectroscopy, upon dehydration, the structure of the supported vanadia changes dramatically. Raman and diffuse reflectance UV-VIS spectroscopy under dehydrated conditions reveal the presence of different vanadia structures (monomers, polymers and crystals) as a function of vanadium loading (0 – 22 wt % V). The maximum coverage of vanadia species on SBA-15 is achieved at ~7.2 wt % V (2.3 V/nm2). At loadings up to 7.2 wt % V, the vanadia species are mainly present as isolated tetrahedral species, whereas at higher loadings V2O5 crystallites are formed, in addition to monomeric and polymeric vanadia species

TiO2 Compact Layers Prepared by Low Temperature Colloidal Synthesis and Deposition for High Performance Dye-sensitized Solar Cells

Compact layers are used in dye-sensitized solar cells (DSSCs) to passivate transparent conducting oxides (TCOs). TCO passivation increases DSSC performance by reducing electrical loss from recombination at the TCO-electrolyte interface and by improving electrical contact between the TCO and TiO2 photoelectrode. A novel process for synthesis of 4.5 nm colloidal TiO2 compact layer particles via acid hydrolysis of titanium isopropoxide was developed. DSSCs fabricated with the colloidal TiO2 compact layer, with no compact layer, and those with an RF-sputtered compact layer were evaluated. Relative to a DSSC with no compact layer, the colloidal compact layer improved the short-circuit current density, fill factor, and solar energy conversion efficiency by 17.6%, 4.4%, and 25.3%, respectively. Relative to the sputtered compact layer, the colloidal compact layer improved the short-circuit current density and solar energy conversion efficiency by 5.5% and 5.3%, respectively, with no significant change in the fill factor. The improved DSSC characteristics were attributed to increased shunt resistance due to decreased electrolyte reduction at the TCO-electrolyte interface and decreased series resistance due to improved electrical contact between the TCO and the TiO2photoelectrode