Positional Isomeric π-Conjugated Polyyne Chromophores: Synthesis and Photophysical Properties

Herein we reported the synthesis of three positional isomeric (o-, m-, and p-) π-conjugated polyyne chromophores, in which three diethynylbenzene positional isomers were used as π-conjugated bridges, respectively. Subsequently, the structural characterization of the above positional isomers was accomplished by NMR, MS, IR, etc. Then, their electronic absorption, photoluminescence (PL) emissions, and electrochemiluminescence (ECL) properties were further investigated. The PL emissions of three π-conjugated polyyne chromophores were observed in the wavelength of ~325–510 nm. Interestingly, the para-isomer with a rigid planar π-conjugated structure exhibits the strongest UV-Vis absorption and fluorescence emission. Finally, the ECL measurements indicated that the three π-conjugated polyyne chromophores exhibited stable cathode ECL emission, providing excellent candidate materials for the future design and manufacturing of ECL emitters.