6-(Arylvinylene)-3-bromopyridine Derivatives as Lego Building Blocks for Liquid Crystal, Nonlinear Optical, and Blue Light Emitting Chromophores
文摘
A novel general synthetic strategy, based on a convergent approach, allowed us to prepare a series ofconjugated 6,6'-distyryl-3,3'-bipyridine derivatives via the Suzuki reaction. First, the key electron-donorand electron-acceptor 6-(arylvinylene)-3-bromopyridine building blocks were synthesized by Knoevenagel-or Siegrist-type reactions. Second, some of them were transformed to the corresponding pyridylboronicesters. Finally, for the first time, we successfully demonstrated that such blocks can be homo- and cross-coupled in high yields and multigram scales, leading to noncentrosymmetic or symmetric chromophores.Their mesogenic, electrochemical, and optical properties have been investigated depending on the electronicstructure. In this series, push-pull compounds are liquid crystals and promising for NLO applications.Whatever the structure, all of these compounds exhibit a high electron affinity and are strongly fluorescent.As an application, lasing properties of one push-pull and one symmetrical compound are reported. Inaddition, a blue-emitting LED was fabricated whose performances at 10 mA/cm2 are a luminous efficiencyof 3.9 cd/A, a power efficiency of 1.4 lm/W, and an external quantum efficiency of 2.9%. Thus, thisversatile synthetic route is of particular interest due to the potential applications of the chromophores inseveral optoelectronic fields.