Study On Synthesis,Characterization And Mesomorphic Properties Of Liquid Crystal Compounds Based On Tetrathiafulvalene

In recent years,Tetrathiafulvalene(TTF)and its crystalline derivatives have played an important role in many applications for organic optoelectronic materials because of their excellent optical and electronic properties,and they are a kind of promising molecular building blocks.Tetrathiafulvalene derivatives with mesomorphic properties are extremely important due to the ordered molecular structures in the LC phase structural defects on the macroscopic scale.However,so many TTF derivatives have so far been synthesized,but there are only few TTF derivatives with mesomorphic properties.The development of the liquid crystal materials based on tetrathiafulvalene is limited by the synthesis and separation.We have designed and successfully synthesized a new series of tetrathiafulvalene derivatives which exhibit liquid phase.We introduced different length of 4'-cyanobiphenyl-4-yloxy side groups into the rigid core of tetrathiafulvalene so that the fluidity of liquid crystal molecules could increase gradually.The target compounds were characterized by 1H NMR,13 C NMR,FT-IR and MALDI-TOF-MS.The thermal stability of the target compounds was investigated by thermogravimetric analysis(TGA),and the measurements indicated that both of the compounds 4a~e and compounds 7a~e were highly thermally stable.The liquid crastal behavior of these compounds was investigated by a combination of differential scanning calorimetry(DSC)and polarization optical microscopy(POM).All the synthesized compounds exhibit mesogenic phases in a wide temperature region,no crystallization but vitrifying to form glassy mesogens during cooling from the isotropic melt.Target molecules with different length of flexible chains shows different liquid crystal texture,which indicated that the morphology of liquid crystal is affected by the architecture of the liquid crystal molecular.To study the electron donating property of target compounds,the cyclic voltammetry(CV)measurements were performed.All the target compounds showed two quasi-reversible single-electron oxidation waves,indicating that these compounds are good ?-electron donors.A series of studies indicated that the target compounds have potential to play an important role in organic optoelectronic materials.