The synthesis and characterisation of two series of cyanobiphenyl-based liquid crystal dimers containing sulfur links between the spacer and mesogenic units, the 4',4''-[1,ωalkanediylbis(thio)]bis-[1,1'-biphenyl]-4-carbonitriles (CBSnSCB), and 4'-({ω-[(4'cyano[1,1'-biphenyl]-4-yl)oxy]alkyl}thio)[1,1'-biphenyl]-4-carbonitriles (CBSnOCB), are described. The odd members of both series show twist-bend nematic and nematic phases whereas the even members exhibit only the nematic phase. An analogous cyanoterphenylbased dimer, 3 4-{6-[(4'-cyano[1,1'-biphenyl]-4-yl)thio]-hexyl}[1 1 ,2 1 :2 4 ,3 1-terphenyl]-1 4carbonitrile (CT6SCB), is also reported and shows enantiotropic NTB and N phases. The transitional properties of these dimers are discussed in terms of molecular curvature, flexibility and biaxiality. The same molecular factors influence also birefringence of nematic phases. Resonant X-ray scattering studies of twist-bend nematic phase at both the carbon and sulfur absorption edges were performed, which allowed for determination of critical behaviour of helical pitch at the transition to nematic phase, the behaviour was found independent on molecular structure. It was also observed that despite the different molecular bending angle and flexibility, in all compounds the helical pitch length far from the N-NTB transition corresponds to 4 longitudinal molecular distances.
The syntheses and characterisation of the first ten homologues of the 1-(4-cyanobiphenyl-4′-yl)-6-(4-alkylanilinebenzylidene-4′-oxy)hexanes (CB6O.m) are reported.
A number of liquid crystal dimers have been synthesised and characterised containing secondary or tertiary (N-methyl) benzanilide-based mesogenic groups. The secondary amides all form nematic phases, and we present the...
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.