Synthesis And Properties Of Fluorescent Dichroic Dyes Based On Guest-Host Effect

Fluorescent "guest-host" liquid crystals (GH-LCDs) have been proposed as a promising display for practical application. Fluorescent GH-LCDs which are characterized by either anisotropic absorption or anisotropic emission can combine the excellent hues and high brightness levels of emissive displays with the desirable features of LCDs. So fluorescent GH-LCDs, which can increase the brightness, the efficiency of light utilization and the viewing angle are proposed as a less enery consuming display for portable electronics. Among the most important problems at the practical utilization of this type of display is the choice of suitable fluorescent dichroic dyes.In order to abound the species of fluorescent dichroic dyes, a new series of1.8-dicyanonaphthene fluorescent dichroic dyes have been designed and synthesized. All the dyes exhibit a bright blue fluorescence with fluorescent maxima at411-422nm and half-bandwidths at66nm. These dyes show dichroism when dispered in LC MLC-6237and80C. The order pamater and fluorescent order pamater are up to0.44. It is the first reported that1.8-dicyanonaphthene moleculars have the dichroism. On this basis, we can further explore1.8-dicyanonaphthene derivatives to achieve practical values.The purpose of this study is to develop highly fluorescent dichroic naphthalimide-based compounds. A new type of benzo [de] benzo [4,5] imidazo [2,1-a] isoquinoline7-one have been designed and synthesized. All the dyes emit intense yellow-green fluorescence at500nm with high quantum yields in LC E7. Polarized absorption and fluorescence spectra show that the dyes have good dichroism with the order pamater at0.55-0.65and fluorescent order pamater at0.45-0.57. The dye X1has practical value with the order pamater up to0.65.We expect to synthesize the dye moleculars based on naphthalimide with high solubility to achieve the practical value. Therefore, a type of naphthalimide derivatives containing long flexible chains and ester have been synthesized. These dyes exhibit strong yellow-green fluorescence with quantum yields up to0.70. The crystallization don’t occur in dye-liquid crystal mixture but the order pamater declines dramatically.