Synthesis of Substituted Dibenz[a,c]anthracenes and an Investigation of Their Liquid-Crystalline Properties

• Published in: European journal of organic chemistry 2015-03, Vol.2015 (7), p.1456-1463
• Main Authors: Psutka, Katie M., Williams, Joshua, Paquette, Joseph A., Calderon, Oliver, Bozek, Kevin J. A., Williams, Vance E., Maly, Kenneth E.
• Format: Article
• Language: English
• Subjects: Aromatic synthesis; Liquid crystals; Pi interactions; Polycyclic aromatic compounds; Self-assembly
• ISSN: 1434-193X; 1099-0690
• DOI: 10.1002/ejoc.201403504

We report the synthesis of a series of 2,3,5,6‐tetraalkoxydibenz[a,c]anthracenes bearing substituents (H, OCH3, or CN) in the 11‐ and 12‐positions and an investigation of their liquid‐crystalline properties. The synthesis involved Suzuki coupling of the appropriate dibromonaphthalene and boronate ester, followed by an oxidative cyclization. Compounds 4 and 5, bearing OCH3 and H, respectively, do not exhibit any liquid‐crystalline properties. In contrast, compounds 6a–c, bearing cyano groups, assemble into columnar mesophases, suggesting that electron‐withdrawing groups are important for promoting columnar mesophase assembly. Analysis of the XRD revealed that compound 6b exhibits a columnar hexagonal phase, whereas compounds 6a and 6c exhibit columnar rectangular phases. The XRD data of 6a and 6b also show reflections that are consistent with antiparallel dimers within the columnar stacks, and intercolumnar spacings suggest that molecules are tilted within the columns. The synthesis of a series of novel dibenz[a,c]anthracenes is described. The dicyano‐substituted derivatives exhibit columnar mesophases and are consistent with antiparallel stacking and a tilted arrangement within the columns.