A Selective C−H Deprotonation Strategy to Access Functionalized Arynes by Using Hypervalent Iodine

Described here is an efficient method to access highly functionalized arynes from unsymmetrical aryl(mesityl)iodonium tosylate salts. The iodonium salts are prepared in a single pot from either commercially available aryl iodides or arylboronic acids. The aryne intermediates are generated by ortho‐C?H deprotonation of aryl(mesityl)iodonium salt with a commercially available amide base and trapped in a cycloaddition reaction with furan in moderate to good yields. Coupling partners for the aryne intermediates beyond furan are also described, including benzyl azide and alicyclic amine nucleophiles. The regio‐ and chemoselectivity of this reaction is discussed and evidence for the spectator aryl ligand of the iodonium salt as a critical control element in selectivity is presented.     

Linear Optical and Third‐Order Nonlinear Optical Properties of Some Fluorenyl‐ and Triarylamine‐Containing Tetracyanobutadiene Derivatives

The synthesis and characterization of four new tetracyanobutadiene (TCBD) derivatives ( 1 – 3 and 2′ ) incorporating 2‐ or 2,7‐fluorenyl and diphenylamino moieties are reported. The electroactivity of 1–3 and 2′ was studied by cyclic voltammetry (CV), while the linear optical and (third‐order) nonlinear optical (NLO) properties were investigated by electronic spectroscopy and Z‐scan studies, respectively. All experimental investigations were rationalized by DFT computations, providing an insight into the electronic structure of these derivatives and on their application potential. We show that these derivatives are nonluminescent in solution at ambient temperatures, but become fluorescent in solvent glasses. This finding constitutes an unprecedented observation for TCBD derivatives. Also, we show by Z‐scan studies that these derivatives behave as two‐photon absorbers in the near‐IR range (800–1050 nm). These third‐order NLO properties are discussed and compared with those of their alkynyl precursors ( 4 – 6 ), which have been investigated by two‐photon excited fluorescence (TPEF).     

From Perylene to a 22‐Ring Aromatic Hydrocarbon in One‐Pot

The successful synthesis of a threefold symmetric C₇₈H₃₆ molecule with 22 fused benzene rings is reported. This clover‐shaped nanographene was characterized on an ultrathin insulating film with atomic resolution by scanning probe microscopy.