Influence of spacer chain lengths and polar terminal groups on the mesomorphic properties of tethered 5-phenylpyrimidines

• Gundula F. Starkulla,
• Elisabeth Kapatsina,
• Angelika Baro,
• Frank Giesselmann,
• Stefan Tussetschläger,
• Martin Kaller and
• Sabine Laschat

Beilstein J. Org. Chem. 2009, 5, No. 63, doi:10.3762/bjoc.5.63

• maximum phase width was observed for the C5 spacer regardless of the terminal group, whereas the hydroxy- and cyano-substituted derivatives 5 and 7, respectively, were non mesomorphic and showed only melting transitions. Keywords: calamitic; liquid crystals; 5-phenylpyrimidines; Introduction A

• tremendous amount of work has been done on calamitic liquid crystals, which has led to applications in the field of LC displays [1]. Among the large family of various calamitic mesogens 2-alkoxy-5-phenylpyrimidines 1 are prominent members due to the fact that the two nitrogen atoms increase the polarity of

• twisted conformation with a dihedral angle of 43.1° [3]. The different conformations together with differences of the polarisation and dipole moment between 2- and 5-phenylpyrimidines also lead to different mesomorphic properties as was shown by Lemieux for phenylpyrimidines tethered to terminal