Probing the structural features that influence the mesomorphic properties of substituted dibenz[a,c]anthracenes

We report the synthesis and mesophase characterization of a series of novel hexaalkoxydibenzanthracenes to probe the effect of side-chain length variation and substituents on the mesophase temperature range. A series of hexaalkoxydibenz[a,c]anthracenes ( 2a – 2i ) with varying chain lengths were pre...

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Bibliographic Details
Published in:	Canadian journal of chemistry Vol. 95; no. 4; pp. 399 - 409
Main Authors:	Paquette, Joseph A, Psutka, Katie M, Yardley, Colin J, Maly, Kenneth E
Format:	Journal Article
Language:	English
Published:	Ottawa NRC Research Press 01-04-2017 Canadian Science Publishing NRC Research Press
Subjects:	aromatic compounds auto-assemblage Bromination Chains Chemical synthesis composés aromatiques Coupling cristaux liquides Electrons Esters interactions pi liquid crystals Mesophase Methods Observations Phases Polycyclic aromatic hydrocarbons self-assembly Stability Stacks Substitutes Substitution reactions synthesis synthèse Temperature π–π interactions
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Summary:	We report the synthesis and mesophase characterization of a series of novel hexaalkoxydibenzanthracenes to probe the effect of side-chain length variation and substituents on the mesophase temperature range. A series of hexaalkoxydibenz[a,c]anthracenes ( 2a – 2i ) with varying chain lengths were prepared by Suzuki coupling of the appropriate boronate ester with the corresponding dialkoxydibromonaphthalenes, followed by oxidative cyclization. Compounds 2a – 2i were also brominated in the 10 and 13 positions to yield the corresponding dibromo series, 4a – 4i . While none of the compounds, 2a – 2i , exhibited columnar mesophases, all of the compounds in series 4a – 4i did exhibit columnar phases over broad temperature ranges. To further investigate the effect of substituents on the mesomorphic properties of hexaalkoxydibenzanthracenes, we also prepared iodo-substituted 8 , nitro-substituted 9 , and amino-substituted 10 . A comparison of the mesophase temperature range with previously reported compounds 3 – 7 shows that electron-withdrawing groups promote the formation of stable mesophases. However, our results also suggest that the substituents affect mesophase stability by participating in intermolecular contacts within the columnar stacks of the mesophase.
ISSN:	0008-4042 1480-3291
DOI:	10.1139/cjc-2016-0505