Beilstein J. Org. Chem.2012,8, 25–49, doi:10.3762/bjoc.8.4
[77]. Terphenyl-bridged bis(benzimidazolium) salts 71, soluble in water and common organic solvents, emit blue light with λmax,em at 420–441 nm in thin films [78]. This feature makes them potentially applicable as blue-light emitters in OLEDs.
Benzimidazole-based push–pull systems were studied also
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Graphical Abstract
Figure 1:
Schematic representation of organic D-π-A system featuring ICT.
Beilstein J. Org. Chem.2009,5, No. 83, doi:10.3762/bjoc.5.83
stabilization of the nematic phase, upon CH2→O replacement, was observed in p-carborane mesogens relative to benzene analogues. Thus, in series 1–4, the nematic phase is stabilized by about 14 K more for the pairs 1A/2A and 3A/4A, than for terphenyl (D) and bicyclo[2.2.2]octane (C) analogues (Figure 2
(SmA and SmB), while the terphenyl analogues display a rich smectic polymorphism involving mainly tilted phases. The terphenyl derivatives 14D[6] and 16D[6] exhibit the most interesting polymorphism in the series with 4 smectic phases and possibly a soft crystalline modification such as a G phase below
the SmF phase in the latter. A DSC trace for 16D[6] is shown in Figure 3, and representative textures of its mesophases are presented in Figure 4. The tilted phases in both terphenyl compounds were identified by the appearance and subsequent characteristic changes of the Schlieren textures in the
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Graphical Abstract
Figure 1:
The molecular structures of 1,12-dicarba-closo-dodecaborane (12-vertex p-carborane, A) and 1,10-dic...