Synthesis of Bench-Stable Diarylmethylium Tetrafluoroborates

A representative number of bench-stable nonsymmetric diarylcarbenium tetrafluoroborates have been isolated via the direct coupling of aryl (or heteroaryl) aldehydes and <i>N</i>-heteroarenes and fully characterized. They have proven to be highly stable in the presence of both EDG and EWG substituents. An (<i>E</i>)-iminium vinylogous substructure has been shown as the common cation scaffold by X-ray analysis and by NOE determination

Organocatalytic Enantioselective Alkylation of Aldehydes with [Fe(bpy)₃]Br₂ Catalyst and Visible Light

Catalytic amounts (2.5 mol %) of [Fe­(bpy)₃]­Br₂ complex in the presence of visible light and the MacMillan catalyst <b>3</b> (20 mol %) are highly effective in promoting an enantioselective organocatalytic photoredox alkylation of aldehydes with various α-bromo carbonyl compounds. Reaction yields of isolated compounds and enantioselectivities are very good and comparable to the ones obtained by [Ru­(bpy)₃]²⁺, organic dyes, or semiconductors, in the presence of the same organocatalysts. The use of first-row, abundant, and cheap metals in photocatalyzed reactions can open new perspectives in stereoselective organic synthesis

Photocatalytic Radical Alkylation of Electrophilic Olefins by Benzylic and Alkylic Zinc-Sulfinates

Alkyl radicals are obtained by photocatalytic oxidation of readily prepared or commercially available zinc sulfinates. The convenient benzylation and alkylation of a variety of electron-poor olefins triggered by the iridium­(III) complex <b>6</b> Ir­[dF­(CF₃)­ppy]₂(dtbbpy)­PF₆ as photocatalyst is described. Moreover, it is shown that zinc sulfinates can be used for facile nonradical sulfonylation reactions with highly electrophilic Michael acceptors

Self-Assembled Two-Dimensional Supramolecular Networks Characterized by Scanning Tunneling Microscopy and Spectroscopy in Air and under Vacuum

We combine ambient (air) and ultrahigh vacuum (UHV) scanning tunneling microscopy (STM) and spectroscopy (STS) investigations together with density functional theory (DFT) calculations to gain a subnanometer insight into the structure and dynamic of two-dimensional (2D) surface-supported molecular networks. The planar tetraferrocene-porphyrin molecules employed in this study undergo spontaneous self-assembly via the formation of hydrogen bonded networks at the gold substrate–solution interface. To mimic liquid phase ambient deposition conditions, film formation was accomplished in UHV by electro-spraying a solution of the molecule in chloroform onto an Au(111) substrate, thereby providing access to the full spectroscopic capabilities of STM that can be hardly attained under ambient conditions. We show that molecular assembly on Au (111) is identical in films prepared under the two different conditions, and in good agreement with the theoretical predictions. However, we observe the contrast found for a given STM bias condition to be different in ambient and UHV conditions despite the similarity of the structures, and we propose possible origins of the different imaging contrast. This approach could be valuable for the thorough characterization of surface systems that involve large molecules and are prepared mainly in ambient conditions