Electrosynthesis and characterization of oligophenylene deriving from 4-(methoxyphenyl)acetonitrile

► The anodic oxidation of p-methoxyphenylacetonitrile led to a conjugated oligophenylene. ► The chemical structure was elucidated by different spectroscopic techniques. ► A mechanism for the electro-oxidative oligomerization was evoked in the light of a DFT theoretical calculation. ► A photoluminescence study: blue emission in solution state and red emission in solid state. An oligophenylene deriving from the 4-(methoxyphenyl)acetonitrile (MPA), was electrosynthesized by direct anodic oxidation at a constant potential in acetonitrile on a platinium electrode. This oligomer (OMPA) showed a good solubility in common organic solvents. The results of osmometry and gel permeation chromatography analyzes indicated that the average chain length for OMPA was about 5 units. Its chemical structure was elucidated by 1H and 13C NMR, FTIR and UV spectroscopy. A thermal study carried out by thermogravimetric analysis and Differential Scanning Calorimetry showed that the oligomer was stable up to 268°C. In addition, the photoluminescent properties of OMPA were investigated. In solution, an emission was recorded in the indigo-blue region, however, in solid state this emission was shifted to the orange–red zone. Finally a mechanism for the electro-oligomerization was evoked in the light of the electronic structures of the MPA and its radical cation obtained by DFT calculation.