Anthracene- and thiophene-containing MEH-PPE-PPVs: Synthesis and study of the effect of the aromatic ring position on the photophysical and electrochemical properties

Abstract

This contribution reports on the synthesis and characterization of thio-phene- (P1, P2, and P3) and anthracene- (P4 and P5) containing PPE-PPV copolymers. The thermostable, soluble and film-forming polymers were fully characterized by NMR, IR and Elem. Anal.; they exhibit high molar masses with polydispersity indices below 2.5. The position of the thiophene in the polymeric backbone has insignificant influence on the spectroscopic properties of the polymers. In contrast, the anthracene-containing polymers reveal position dependent optical properties. A constant bathochromic shift of 50 nm was observed going from P4, where anthracene is surrounded by two double bonds, to P5, where anthracene is at the bridge between a triple bond and a double bond, as well as from P5 to P6 where anthracene is surrounded by two triple bonds. This correlates to the decrease of the observed anthracene band around 255 nm going from P4 through P5 to P6, amounting to the degree of contribution of the anthracene unit to the main chain conjugation. The phenomenon known as CN-PPV effect was observed in the case of P4 [φf (solution) = 3%, φf (solid) = 13%]. Electrochemical studies carried out under absolute inert conditions revealed lower electrochemical band gap energies, Eecg, than Eoptg. © 2009 Wiley Periodicals, Inc.