Synthesis, characterization and optical properties of a series of copolymers bearing 1-ethynylpyrene and ethynylbenzene units

Abstract

A novel series of copolymers were obtained from the copolymerization of 1-ethynylpyrene (EP) (known as pyrenylacetylene) and ethynylbenzene (EB) (named also phenylacetylene) with WCl6 as catalyst and toluene as solvent, using different monomer molar ratios EP/EB (80:20, 60:40, 50:50; 40:60, 20:80). The optical properties of the obtained copolymers Poly(EP-co-EB) were determined by absorption and fluorescence spectroscopy. Absorption spectra of the copolymers Poly(EP-co-EB) showed that copolymers containing phenylacetylene units possess a lower degree of conjugation than the homopolymer trans-poly(1-ethynylpyrene) (trans-PEP), since they showed a twisted conformation. These results were confirmed by emission spectroscopy showing the formation of excimers for those copolymers containing high pyrene content.