Liquid crystal oligomers: going beyond dimers

Synthesis mesomorphic and theoretical studies of some new unsymmetrical dimeric ethers of 6-amino-1,3-dimethyluracil and biphenyl cores

“…The same effect is observed in present series of compounds with increasing carbon atoms in both the terminal and spacer alkyl chain. The results are found here are unusual when compare to the normal behaviour of the dimers [35].…”

Twist-bend heliconical chiral nematic liquid crystal phase of an achiral rigid bent-core mesogen

“…For example, modification of CB7CB with alkoxy chain terminal, only dimers with short terminals (n=4) are able to form the N TB phase [23]. If the bent shape is lost altogether, for example in odd-numbered trimers, no N TB phase is observed [24].…”

Developments in liquid-crystalline dimers and oligomers

“…The reaction proceeded smoothly without hydrodefluorination or reduction of the nitrile to a benzylamine and was complete within 2 h in all cases. The products (16/17) and the starting materials (14/ 15) could be easily distinguished by 1 H NMR spectroscopy due to the difference in chemical shift of a CH 2 adjacent to an aromatic ring versus a CH 2 adjacent to an alkyne, as well as differences in two of the aromatic proton environments as shown in Figure 6. Furthermore, workup of the hydrogenation was trivial and chromatography free; the reaction mass was filtered through a packed bed of celite, dried in vacuo, redissolved in DCM onto which ethanol was layered, affording the tetramesogens 16 and 17 as microcrystalline solids.…”

“…Joining two identical rod-like units together affords a dimer, three units afford a trimer and n units afford an oligomer [1][2][3][4]. However, if we join together n mesogenic units that are not identical, such as roddisc systems [5], then it is preferable to use the terms bimesogen (n = 2), trimesogen (n = 3), tetramesogen (n = 4) and oligomesogen.…”