Synthesis and mesomorphism of mixed ether-ester tail triphenylene discotic liquid crystals with long alkyloxy peripheral chains

Abstract

Symmetrical and asymmetrical triphenylene discotic liquid crystals with two kinds of different peripheral chains, sym-TP(OC11H23)3(O2CR)3 and asym-TP(OC11H23)3(O2CR)3, (R=CH2OC2H5, CH2OC3H7, CH2OC4H9, CH2OC5H11, C3H7, C4H9, C5H11, C6H13, C7H15) were synthesized. Their thermotropic liquid crystalline properties were studied by polarizing optical microscopy (POM) and differential scanning calorimetry (DSC). The results showed that the asymmetrical compounds had higher melting and clearing points than that of their corresponding symmetrical compounds. For the same series of compounds, TP(OC11H23)3(O2CR)3, their melting points decrease and clearing points increase gradually with the lengthening of ester chains. Most of the β-oxygen containing esters of triphenylene derivatives, TP (OC11H23)3(O2CR)3, (R=CH2OC2H5, CH2OC3H7, CH2OC4H9, CH2OC5H11), symmetrically or asymmetrically attached on triphenylene cores, have higher melting and clearing points than those of triphenylene derivatives, TP(OC11H23)3(O2CR)3, (R=C4H9, C5H11, C6H13, C7H15), with the same length of peripheral chains. The triphenylene derivatives with longer peripheral chains have shown mesophase at room temperature.