Liquid crystal properties of triphenylene esters.

Samman, Saeed (2022) Liquid crystal properties of triphenylene esters. Doctoral thesis, University of East Anglia.

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Designing discotic liquid crystals often involves ester linkages. Hexaesters of benzene were the first examples of discotic liquid crystals reported by Chandrasekhar.

This thesis presents the synthesis and investigation of monoesters, diads, and diesters of triphenylene.

We present examples of materials that combine linked and twinned design elements to induce the onset of nematogenic behaviour. In the case of pentahexyloxy triphenylenes containing a single aryl ester plus five hexyloxy substituents, the columnar mesophase is retained. Additionally, the stability of the mesophases is not significantly affected by the ester used. In isomeric series (phthalates), linked dyad structures promote nematic phase formation and stability depends on the type of link and the bonding arrangement. Another ester linked dyad system has been prepared from diacid chlorides. For ferrocene links, the geometry can be considered to have intermediate switches between staggered and eclipsed arrangements. The staggered formation of this arrangement makes it unlikely to support liquid crystal behaviour, and this is indeed observed. A further ester-linked dyad system was prepared by new route (biphenyl route). This new dyad structure was characterized and demonstrated columnar liquid crystal behaviour.

Finally, we synthesized and examined a series of triphenylenes bearing two aryl esters and four hexyloxy substituents. The aim was to couple 2,3-dihydroxy triphenylene and 3,6-dihydroxy triphenylene with benzoate by the same method as previously used.

The mesophases formed in all examples are columnar hexagonal; clearing temperatures are higher than for monoesters but again the ester employed does not to affect their stability.

Item Type: Thesis (Doctoral)
Faculty \ School: Faculty of Science > School of Chemistry
Depositing User: Chris White
Date Deposited: 29 Mar 2023 08:15
Last Modified: 29 Mar 2023 08:15


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