Copper Causes Regiospecific Formation of C4F8‐Containing Six‐Membered Rings and their Defluorination/Aromatization to C4F4‐Containing Rings in Triphenylene/1,4‐C4F8I2 Reactions

The presence of Cu in reactions of triphenylene (TRPH) and 1,4‐C₄F₈I₂ at 360 °C led to regiospecific substitution of TRPH ortho C(β) atoms to form C₄F₈‐containing rings, completely suppressing substitution on C(α) atoms. In addition, Cu caused selective reductive‐defluorination/aromatization (RD/A) to form C₄F₄‐containing aromatic rings. Without Cu, the reactions of TRPH and 1,4‐C₄F₈I₂ were not regiospecific and no RD/A was observed. These results, supported by DFT calculations, are the first examples of Cu‐promoted 1) regiospecific perfluoroannulation, 2) preparative C?F activation, and 3) RD/A. HPLC‐purified products were characterized by X‐ray diffraction, low‐temperature PES, and ¹H/¹⁹F NMR.     

Penimethavone A,a flavone from a gorgonian-derived fungus Penicillium chrysogenum

A novel flavone, penimethavone A (1), possessing a rare unique methyl group at ring-B, was isolated from the fungus Penicillium chrysogenum cultured from a gorgonian Carijoa sp. collected from the South China Sea. The structure was elucidated by extensive spectroscopic analysis and by comparison with related known compound. Compound 1 showed selective and moderate cytotoxicity against cervical cancer (HeLa) and rhabdomyosarcoma cell lines with IC₅₀ values of 8.41 and 8.18 μM, respectively.     

Star-PDMAEMA-β-CD-Stabilized Colloidal Gold Nanoparticles: Synthesis,Characterization and pH-Controlled Assembly

Colloidal gold nanoparticles were prepared through in situ reduction in the presence of water-soluble star homopolymer with β-cyclodextrin core and poly[2-(dimethylamino) ethyl methacrylate] arms (star PDMAEMA-β-CD) at ambient temperature. In this process, star PDMAEMA-β-CD acted as both reducing agent and stabilizing agent for gold nanoparticles. More importantly, the optical properties and the morphology of star-PDMAEMA-β-CD-stabilized colloidal gold nanoparticles were sensitive to the solution pH due to structural changes of the polymer. Different assemblies can be formed by tuning the pH of the medium. Fourier transform infrared (FT-IR), UV-Vis absorption spectroscopy, transmission electron microscopy (TEM), dynamic laser light scattering (DLS) and X-ray diffraction (XRD) were used to characterize the synthetic gold nanoparticles and the pH-controlled assembly of gold nanoparticles.     

Photoelectrocatalytic decomposition of gaseous isopropanol in a polymer electrolyte photoreactor

A photoelectrochemical reactor constructed as a proton exchange membrane fuel cell was utilized to electrochemically enhance the photocatalytic decomposition of gas-phase isopropanol. Nafion membrane was employed to serve as solid electrolyte to establish an electrochemical circuit for the gaseous photocatalytic reaction. The electrical current density of photoanode was found to correspond to the variation of the applied bias and relative humidity of the inlet gas. Photocatalytic decomposition rate was remarkably increased by 20 % by applying a bias potential of 5 V. The effect of relative humidity exhibited multiple effects for membrane conductivity of Nafion and efficiency of photocatalytic decomposition reaction.