Palladium-catalysed direct regioselective C5-arylation of a thiophene bearing a cyclopropyl ketone group at C2

A thiophene bearing a cyclopropyl ketone group at C2 was successfully employed in palladium-catalysed direct arylation. The reaction proceeds regioselectively at C5 without decomposition of the cyclopropyl ketone substituent. These couplings were performed employing as little as 0.5 mol% of ligand-free Pd(OAc)₂ catalyst with electron-deficient aryl bromides. A wide variety of functional groups on the aryl bromide such as nitrile, nitro, acetyl, formyl, benzoyl, ester, trifluoromethyl, fluoro or methoxy was tolerated. © 2013 Elsevier Science. All rights reserved.     

The synthesis and electrochemical properties of a new tetra-(crown-ether-thiafulvalene)-annulated phthalocyanine derivative

A novel, metal-free, crown-ether-tetrathiafulvalene annulated phthalocyanine was synthesized by tetramerization of the corresponding phthalonitrile derivative; both compounds were characterized by elemental analysis, IR, UV–vis, DPV or CV and MS spectra. The crystal structure of the precursor was determined by X-ray crystallography. The charge transfer absorption bands of the two compounds lay ～400 nm after addition of 7,7,8,8-tetracyanoquinodimethane. Electrochemical studies revealed that both compounds displayed good complexation selectivity for Na⁺ ion with large positive redox shifts, indicating that they may be a new redox-active sensor.     

The syntheses,structures and nonlinear optical and related properties of salts with julolidinyl electron donor groups

Twelve, dipolar cations with 2,3,6,7-tetrahydro-1H,5H-pyrido[3,2,1-ij]quinolin-9-yl (julolidinyl, Jd) electron donor groups and N-methyl/arylpyridinium, N-methylquinolinium or N-methylbenzothiazolium acceptor groups were synthesised. The chromophores were characterised as their PF₆^? salts using various techniques including electronic absorption spectroscopy and cyclic voltammetry; single crystal X-ray structures were determined for a large number of salts, all of which form nonpolar materials. A broad correlation between the electron acceptor strength and the degree of bond length alternation is evident. A key focus of this work is detailed comparisons of the Jd-containing chromophores with their previously studied 4-(dimethylamino)phenyl (Dap) analogues. Molecular, quadratic, nonlinear optical responses were determined using femtosecond hyper-Rayleigh scattering at both 1300 and 800 nm, as well as using Stark (electroabsorption) spectroscopic studies of intense, visible π → π¹ intramolecular charge-transfer bands. Substantial red shifts in the latter transitions are observed on replacing Dap with Jd which indicate that the latter acts as a more effective π-electron donor. With few exceptions, both hyper-Rayleigh scattering and Stark data generally show that using Jd instead of Dap increases the static first hyperpolarizability β₀, in accord with expectations based on the two-state model. β₀ values as high as 6 times larger than that of the chromophore in the technologically important material E-4′-(dimethylamino)-N-methyl-4-stilbazolium tosylate are observed.     

Rigorous diffraction simulations of topographic wafer stacks in double patterning

Double patterning is regarded as a potential candidate to achieve the 32 nm node in semiconductor manufacturing. A key problem for a standard litho-etch–litho-etch (LELE) double patterning process is to evaluate and tackle the impact of the wafer topography resulting from the hardmask pattern on the second lithography step. In this paper, we apply rigorous electromagnetic field (EMF) solvers to investigate the wafer topography effects. At first, the studied 3D mask is split into two masks. The topography resulting from the exposure with the first split mask is described by a patterned hardmask. Based on that, the bottom antireflective coating (BARC) thickness of the second wafer stack is optimized. Alternatively, a two beam interference and the full diffraction spectrum of the second mask are used as the illumination of the wafer stacks, respectively. Finally, simulated 3D resist profiles for different BARC thicknesses are shown. The importance of wafer topography impact, the optimization of topographic wafer stacks, and the possible solutions to compensate for the impact of the wafer topography are discussed.     

Ligandless Suzuki–Miyaura reaction in neat water with or without native β-cyclodextrin as additive

Efficient green ligand-free Suzuki cross coupling in neat water was developed by using low loading of catalyst (0.5 mol%) in neat water in the presence or not of β-cyclodextrin (0.5 mol%) as additive at 25 °C and 100 °C respectively.     

Preparation of belt-like aggregates of a perylene derivative

Perylene 3,4,9,10-tetracarboxylic tetraethyl ester (PTCTEE) was synthesized via an esterification of perylene 3,4,9,10-tetracarboxylic dianhydride (PTCDA) with ethanol and iodoethane. After the chloroform solution of PTCTEE was mixed with n-hexane the luminescence intensity decreases, indicating the aggregation of the PTCTEE molecules. The characterizations of AFM and TEM showed that PTCTEE could form belt-like aggregates in this mixed solvents. The process of the formation and growth of the belt-like aggregates was tracked using AFM and the relation between the length of the belt-like aggregates and time could be well described using an exponential function. This aggregate growth is a one-dimensional crystallization of the PTCTEE molecules mainly due to the strong π–π stacking ability of perylene cores. The proper interaction between the side chains and solvent also plays an important role in creating one-dimensional aggregates of PTCTEE.     

Positron annihilation investigation of vacancies in as-grown and electron-irradiated diamonds

Vacancy-type defects in the four main types of diamond (Ia, Ib, IIa and IIb) were investigated using positron lifetime, Doppler broadening and optical absorption spectroscopies. In unirradiated samples vacancy clusters were found in all types, synthetic as well as natural. These clusters are situated in highly defected regions, rather than homogeneously distributed, and their concentration varies significantly from sample to sample. For synthetic Ib diamonds vacancy clusters were investigated as a function of nitrogen content. The bulk lifetime for diamond is calculated to be 98±2 ps and the bulk Doppler S parameter is estimated to be 25% lower than that for silicon. Electron irradiation (2.3 MeV) produced neutral monovacancies in IIa diamond and the positron data correlated well, as a function of dose, with the GR1 optical zero-phonon line; the introduction rate was estimated to be 0.5±0.2 cm⁻¹. In Ib diamond, monovacancies were found to be negatively charged. The positron lifetime for monovacancies was (40±6)% larger than the bulk lifetime and the Doppler S parameter increased by (8±1)%. At-temperature Doppler measurements between 30 and 770 K indicated that irradiation-produced neutral monovacancies can convert to the negatively charged state above 400 K but this was dependent on diamond type. Isochronal annealing of irradiated Ib diamonds showed that the complex of a substitutional nitrogen and a vacancy, formed upon annealing close to 600°C, undergoes two detectable modifications between 600 and 870°C reaching a configuration stable to 1170°C. Key conclusions based on positron and optical data are in mutual accord.     

Solvent-induced generation of two magnesium-based metal–organic frameworks with doubly inter-penetrated ReO3 nets constructed from the same linkers but distinct inorganic nodes

Through changing the components of solvent, two Mg-based metal–organic frameworks were synthesized, which possess the same two-fold interpenetrated ReO₃ net constructed by identical linkers, 4,4′,4″-benzene-1,3,5-triyl-tribenzoate, but distinct nodes, Mg₂ and Mg₆ units, respectively. Here, DMSO and water are key factors for forming hexanuclear clusters, while DMF and DMSO act as template reagents for constructing super-octahedral cavities.     

Sequential Ruthenium(II)-Acetate Catalyzed C–H Bond Diarylation in NMP or Water and Hydrosilylation of Imines

Ruthenium(II)-acetate catalysts are shown to promote sp² C–H bond activation/diarylation of arylimines with aryl bromides selectively at ortho positions in both organic solvent (N-methylpyrrolidone, NMP) and in water. Water allows to produce a more active ruthenium catalyst for diarylation of ketimines. Furthermore, the diarylation of imines in water in basic media allows the access to diarylated aldehyde. Sequential catalytic C–H arylation/reduction using either a stoichiometric amount of NaBH₃CN or via a ruthenium(II) catalytic hydrosilylation of the resulting imines offers a direct route to bulky secondary amines.