Synthesis and Optical Properties of New Chalcones Containing a 3,4-Ethylenedioxythiophene Fragment

A new series of chalcones bearing two or more 3,4-ethylenedioxythiophene fragments were synthesized, and their optical properties were studied. The Stokes shifts (Δλ) and band gaps (Egopt) were calculated on the basis of the absorption and emission spectra. The largest Stokes shift (115 nm) was found for a symmetrical product of the terephthalaldehyde and 3,4-ethylenedioxythiophene-2-carbaldehyde condensation, and the smallest band gap (1.93 eV) is characteristic of a chalcone that contains a 2,2',5',2''-ter(3,4-ethylenedioxythiophene). Correlations were established between the band gap and mutual arrangement of the 3,4-ethylenedioxythiophene fragments in the prepared chalcones.