Conformational analysis of the biphenyl moiety of dimer liquid crystals in the solid state by high-resolution solid-state 13C NMR and ab initio GIAO-CHF calculations

✍ Scribed by Renato Norio Shimizu; Hiromichi Kurosu; Isao Ando; Akihiro Abe; Hidemine Furuya

• Publisher: John Wiley and Sons
• Year: 1999
• Tongue: English
• Weight: 98 KB
• Volume: 37
• Category: Article
• ISSN: 0749-1581
• DOI: 10.1002/(sici)1097-458x(199907)37:7<479::aid-mrc482>3.0.co;2-j

✦ Synopsis

High-resolution 13 C NMR spectra of ˛,ω-bis[(4,4 0 -cyanobiphenylyl)oxy]alkanes (CBA-n, n D 7, 9 and 10) were measured in chloroform solution and in the polycrystalline state. The spectra of the samples in solution are essentially the same; in the polycrystalline state, on the other hand, the spectrum of CBA-9 presents some differences in the aromatic carbon region in relation to those of CBA-7 and CBA-10 0 which are similar. Therefore, ab initio GIAO-CHF calculations were carried out and an analysis of the conformation of the biphenyl moiety was attempted by comparing the results of the calculations with the measured high-resolution solid-state 13 C NMR spectra. From these results it was concluded that the torsion angle for the biphenyl moiety of CBA-7 and CBA-10 stays at about 40 °. For CBA-9 it is suggested that conformers with torsion angles of about 30 °and 60 °are also present. Copyright