New conjugated cruciform chromophores with D-π-A structure: Synthesis, characterization and theoretical calculation

• New conjugated cruciform chromophores were synthesized by crossing coupling reaction.
• The relationship of electron structures and photophysical properties was investigated.
• Theoretic calculation verified the charge transfer pathways from HOMO to LUMO.

The new conjugated cruciform chromophores with donor–acceptor character, 1,4-dithienyl-2,5-bis(diphenylamino-phenyl)benzene (2) and 1,4-bis((5-(E)-2-(5-octylthiophen-2-yl)vinyl)thiophen-2-yl)-2,5-bis(diphenylamno-phenyl)benzene (3), were synthesized by Suzuki and Stille coupling reaction, respectively. Compounds 2 and 3 provided with a certain crystal character. In addition, compound 2 showed bright green emission in both CH2Cl2 solution and solid film. However, compound 3 showed green emission in CH2Cl2 solution and orange emission in solid film, which was attributed to the intermolecular interaction. The cyclic voltammetry (CV) and density functional theory (DFT) researches indicated that the symmetry crossing branches mainly influenced the lowest unoccupied molecular orbital (LUMO) levels. Moreover, DFT investigation indicated that compound 2 possessed the linear charge transfer pathway, and compound 3 may possess three different types of charge transfer pathways in excited state.