Nematogens with more flexible chains than aromatic rings in the core

Mesogens containing four rings in the main core can accommodate one termina l and two nearby lateral chains on each outside aromatic ring. These compou nds containing six chains present an enantiotropic nematic range which is i nfluenced by the rigidity of the links. The conformational behaviour of the first methyleneoxy group within the chains was investigated by one and two dimensional C-13 NMR. The sign of the jump in chemical shifts when enterin g the nematic phase indicates the folding of each lateral branch. Dipolar o scillations during cross-polarization contact provide the values of the bon d order parameter. The two First lateral fragments do not behave in the sam e way, demonstrating the influence of the fragment along which the chain is back: folded.