Synthesis, characterization and liquid chromatographic behaviours of a new chemically bonded liquid crystal

Abstract A new bonded liquid crystal stationary phase (2OC 12 ) for high-performance liquid chromatography was studied. It resulted from coupling of LiChrospher Si 100 NH 2 and a mesogenic carboxylic acid, 4-(4-(4-(3,4-didoceyloxy-styrenyl)phenyl-diazenyl)phenyloxy-methylene) benzoic acid (ILC). ILC was characterized with proton NMR and differential scanning calorimetry, while 2OC 12 was characterized by solid state 13 C NMR and elemental analysis. 2OC 12 surface area was determined by the BET method. The chromatographic behaviour of 2OC 12 was investigated under both normal- and reversed-phase conditions. The plots of ln  k against 1/ T showed transition temperatures at 325 and 337 K. Polyaromatic hydrocarbons (PAHs) were separated using hexane, isooctane or hexane-chloroform. Above the transition temperatures, the bonded material exhibited a liquid crystal-like behaviour: (i) the plate number N was always highest possible, and (ii) the more retained the solute the more elongated it was (anthracene is eluted after phenanthrene, chrysene before tetracene, pentacene after dibenzo-a,h-anthracene). Using acetonitrile/water (60/40), reversed-phase data of aromatic hydrocarbons are similar (highest values of N , better resolution below than during the transitions).