Radical cyclization of sugar-derived beta-(alkynyloxy)acrylates: synthesis of novel fused ethers

[formula: see text] Tributyltin radical mediated cyclization of carbohydrate-derived beta-(alkynyloxy)acrylates leading to highly functionalized cis- and trans-fused bicyclic ethers of various ring sizes is described. The efficacy of the radical cyclization is nicely illustrated in the iterative construction of a trans-fused tricyclic tetrahydropyran.     

Thermally Robust and Tuneable Phosphorescent Gold(III) Complexes Bearing (N^N)-Type Bidentate Ligands as Ancillary Chelates

Phosphorescent mono-cyclometalated gold(III) complexes and their possible applications in organic light emitting diodes (OLEDs) can be significantly enhanced with their improved thermal stability by suppressing the reductive elimination of the respective ancillary ligands. A rational tuning of the π-conjugation of the cyclometalating ligand in conjunction with the non-conjugated 5,5′-(1-methylethylidene)bis(3-trifluoromethyl)-1H-pyrazole were used as a strategy to achieve room-temperature phosphorescence emission in a new series of gold(III) complexes. Photophysical studies of the newly synthesised and characterised complexes revealed phosphorescent emission of the complexes at room temperature in solution, thin films when doped in poly(methyl methacrylate) (PMMA) as well as in 2-Me-THF at 77 K. The complexes exhibit highly tuneable emission behaviour with photoluminescent quantum efficiencies up to 22 % and excited state lifetimes in the range of 63–300 μs. Detailed photophysical investigations in combination with DFT and TD-DFT calculations support the conclusion that the emission properties are strongly dictated by both the cyclometalating ligand and the ancillary chelating ligand. Thermogravimetric studies further show that the thermal stability of the Au^III complexes has been drastically enhanced, making these complexes more attractive for OLED applications.     

Synthesis and Diels-Alder Reactions of a New Kind of Chiral Dienophiles: Cyclic Vinyl-p-tolylsulfilimines

A new kind of chiral dienophiles, cyclic vinyl-p-tolylsulfilimines (2a and 2b), were obtained from the corresponding (Z)-sulfinylacrylonitriles with HBF(4) and methanol. The asymmetric Diels-Alder reaction of optically pure 2a with cyclopentadiene under mild thermal or catalyzed conditions afforded only the endo-4a adduct with complete endo and pi-facial selectivities. The ability of the sulfilimine moiety to enhance the dienophilic reactivity of the double bond is similar to that of the sulfinyl group.     

Vector solitons in (2 + 1) dimensions

We address the problem of the existence and stability of vector spatial solitons formed by two incoherently interacting optical beams in bulk Kerr and saturable media. We identify families of (2+1)-dimensional two-mode self-trapped beams, with and without a topological charge, and describe their properties analytically and numerically.     

Synthesis of derivatives of pyrazolo[1,5-a]pyrrolo[1,2-c][1,3,6]-benzotriazocine,a new class of compounds with potential CNS activity

The synthesis of derivatives of pyrazolo[1,5-a]pyrrolo[1,2-c][1,3,6]benzotriazocine was obtained by the reaction of arylaldehydes with some 1-(2-aminophenyl)-5-(pyrrol-1-yl)pyrazoles, as hydrochlorides. Characterization of this new class of compounds was effected with ir, pmr and ¹³C nmr spectral data.     

Time-of-flight secondary ion mass spectrometric analysis of the interface between bone and titanium implants

Implant healing into bone tissue is a process where the mature bone grows towards and eventually fuses with the implant. In this study we investigated implant healing during 4 weeks with focus on the implant-tissue interface. Our main interest was to study the mineralization process around the implant. Titanium discs were implanted in rat tibia for 2 and 4 weeks. After implantation cross sections of bone and implant were made using a low-speed saw equipped with a diamond wafering blade. One section from each sample was stained with basic fuchsin and micrographed by light microscopy (LM). The other section was analyzed with imaging time-of-flight secondary ion mass spectrometry (TOF-SIMS) using a Bi(3)(+) cluster ion source. This ion source has recently been shown to enable identification of high-mass hydroxyapatite (HA) fragment ions (m/z 291-653) in bone samples. The LM images were used to identify areas suitable for TOF-SIMS analysis. Three areas were selected for mass spectral analysis, corresponding to interface region, bone and soft tissue, from which positive ion spectra were recorded. In the areas identified as bone, high-mass HA fragments ions were found after both 2 and 4 weeks. In the soft tissue area, no high-mass ions were found after 4 weeks. However, after 2 weeks HA-related ions were identified in mineralized spots in areas defined as soft tissue. After 4 but not after 2 weeks, high-mass HA fragment ions were found in the interface region. In conclusion, differences were observed regarding mineralization between 2 and 4 weeks of implantation and between different regions surrounding the implants. Imaging TOF-SIMS analysis using a Bi(3)(+) cluster as ion source enables identification of high-mass HA fragment ions at implant-tissue interfaces in bone. This technique might therefore be useful for biocompatibility assessment and for studying the mineralization process at implant surfaces.