New Liquid Crystalline Conjugated Derivatives of 3,3‘-Bipyridine as Components for Optoelectronic Materials

We present a series of new 6,6‘-distyryl-3,3‘-bipyridine derivatives synthesized via a Knoevenagel condensation reaction and disubstituted with electron donor and acceptor groups. These molecules were characterized by spectroscopic methods (NMR, Raman, UV−vis, photoluminescence). These compounds were all found to exhibit thermotropic liquid crystalline (LC) phases, the structures of which were analyzed by DSC and temperature-dependent X-ray diffraction. The high degree of conjugation and the mesogenic character of these molecules could lead to nonlinear optical (NLO) applications for the “push−pull” compounds. Absorption in the UV range and blue fluorescence are other characteristics of some members of this group. The latter property opens up applications as light-emitting diodes (LEDs).