Simultaneous Dehalogenation and Hydrogenation in Sonogashira Coupling

We herein report a simultaneous dehalogenation and hydrogenation(DHH)reaction in Sonogashira coupling involving hexahalogenobenzene C6X6(X=I,Br),in which a halogen on the aryl polyhalide substrate was substituted by a hydrogen atom.First,a steric bulky terminal alkyne 5 was designed and synthesized to study the influence of the reaction conditions(e.g.,catalyst,solvent,temperature)and the halogens on the substrates C6X6 on the DHH reaction.Moreover,based on the optimized conditions,a terminal alkyne 6 with less steric hindrance was further synthesized to investigate the influence of alkyne on the DHH reaction.As a result,two aromatic polyynes 7 and 8 were were further studied and compared.The influence produced by the alkynes and aryl polyhalides substrate provide insights into Sonogashira coupling involving terminal alkyne with huge steric hindrance and polyhalogenated aromatic hydrocarbons.

Positional Isomeric Thiophene-Based π-Conjugated Chromophores:Synthesis,Structure,and Optical Properties

A series of positional isomeric chromophores o-TC,m-TC,and p-TC,in which electron-rich thiophene moieties were connected byπ-conjugated bridges,were divergently synthesized and characterized.Single-crystal X-ray diffraction analysis revealed an intriguing zipper-like packing mode which was adopted by m-TC in the solid state.Subsequently,UV−vis absorption spectra and fluorescence spectra in a series of solvents were investigated.The nearly coplanar para isomer p-TC was found to have the most intense UV−vis absorption,fluorescence emission,and the highest photoluminescence quantum yield.The molecule structure,electronic nature,and origination of the absorption of p-TC were revealed through density functional theory calculations.Interestingly,all three positional isomers exhibited strong and stable electrochemiluminescence emission,which enriched the existing knowledge on the optical properties of thiophene-based oligomers.