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 in order to probe the effect of side-chain length variation and substituents on the mesophase temperature range. A series of hexaalkoxydibenz[a,c]anthracenes (2a-i) with varying chain lengths were prepared by Suzuki coupling of the appropriate boronate ester with the corresponding dialkoxy-dibromonaphthalenes, followed by oxidative cyclization. Compounds 2a-i were also brominated in the 10 and 13-positions to yield the corresponding dibromo series 4a-i. While none of the compounds 2a-i exhibited columnar mesophases, all of the compounds in series 4a-i did exhibit columnar phases over broad temperature ranges. To further investigate the effect of substituents on the mesomorphic properties of hexaalkozydibenzanthracenes, 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.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author