Aromatic Fluorination Effect on the Mesomorphic Properties of Discotic Liquid Crystal of Alkoxybenzoyloxytriphenylene

Abstract

2,3,6,7,10,11-hexakis (4-alkyloxy-2,3,5,6-tetrafluorobenzoyloxy) triphenylenes ( CnF4 ; n = 6, 7, 8, 9, 10, 12, 14, 16) and the branched peripheral chain derivative [ C6(2C2)F4, C8(3,7C1)F4 and C7(1C1)F4 ] were synthesized to study the mesomorphic transition behavior by polarized optical microscope, DSC and XRD techniques. It was found that CnF4 s exhibit Col_h phase having a wide range of temperature, and the clearing points get slightly lowered as the peripheral chains are elongated. On the other hand, the stabilities of mesomorphism for CnF4s having the branched peripheral chains without C7(1C1)F4 larger then corresponding non-branched peripheral chain homologues. It was shown that the elongation of the peripheral chains and the introduction of branched structure into the chains give no change in the type of mesomorphism, implying a strong attractive interaction among the fluorinated phenyl groups.

Keywords:

• discotic liquid crystal
• hexagonal columnar phase
• tetrafluorobenzene derivatives
• attractive interaction

Notes

br = Broad.

^a Col_t: tetragonal columnar phase, Col_r: rectangular columnar phase, N_D: discotic nematic phase.