Ionic liquid crystals: Synthesis and characterization via NMR, DSC, POM, X-ray diffraction and ionic conductivity of asymmetric viologen bistriflimide salts

Dicationic stilbazolium salts: Structural, thermal, optical, and ionic conduction properties

“…where f0 is the frequency in the limit of high temperatures, B is related to the activation energy of the dielectric relaxation, and T0 is the Vogel temperature, above which molecular motions onset. The VFT parameters are summarized in Table S1, and are comparable to those reported by our group on asymmetric viologen bistriflimide salts [88]. The marked VFT profiles highlight the relevance of segmental motions in the II-3 glass, which also control the short-range conductivity of this salt visible in Fig.…”

“…The strongly linear temperature dependence of this relaxation, Fig. S30, is indicative of local variations of the II-3 dipoles activated by molecular motions, and more specifically, the Ea value ~ 80 kJ mol −1 , is typical of the so-called β-relaxation arising from rotation of rigid dipoles around the long axis of rodlike molecules [88], [90]. Interestingly, the presence of plateaus in σ' with mirroring temperature/frequency dependences as in ε'', Fig.…”

“…Both the dielectric elastic constant, ε', and loss modulus, ε'', have very high values, Fig. 10(a) and 10(b), respectively, explained by the large polarity of ILs [88]. The II-3 ε'' peak in the isotropic range starts decreasing in intensity below crystallization (T < 140 °C), and the new process reported above simultaneously appears and shifts to lower frequencies on further cooling, which is indicative of dielectric relaxations associated to molecular motions in the salt [89].…”

Molecular design of viologens to exhibit low-order liquid-crystalline phases

“…For instance, general viologens with long alkyl chains attached to both ends of a 4,4'-bipyridine core exhibit high-order LC phases. [7][8][9] In contrast, -extended viologens with one aromatic ring attached to each of the 4 and 4' positions of the bipyridine core have been reported to exhibit a low-order LC phase (SmA). [10][11][12] However, none of them exhibit a low-order LC phase at ambient temperature (approximately 2015 °C with no need for temperature control), and there are numerous extended viologens that do not exhibit an isotropic phase because the LC-isotropic phase-transition temperature is higher than the decomposition temperature.…”

Liquid crystal behavior, photoluminescence and gas sensing: A new series of ionic liquid crystal imidazole and benzoimidazole bearing chalcone groups, synthesis and characterization

“…27 Moreover, to investigate the performance of materials in electro-optic devices, ionic conductivity inuence, and the ion size on the stability of the smectic phase, a series of ILCs have been prepared and studied. [28][29][30][31] Likewise, imidazole-based compounds have become an important part of pharmaceutical and medical chemistry, due to the unique desirable structural features of the imidazole ring which include being electron-rich, aromaticity, polarity, being ionizable and other characteristics. 32,33 More importantly, multibinding site imidazole rings are capable of coordination with a variety of inorganic metal ions or interaction with organic molecules through noncovalent bonds to create supramolecular drugs that may not only have the bioactivity of imidazole itself, but also the benets of various supramolecular drugs, possibly exerting doubleaction mechanisms that are helpful to overcome drug resistance.…”