Thermotropic Liquid-Crystalline and Light-Emitting Properties of Bis(4-aalkoxyphenyl) Viologen Bis(triflimide) Salts

Abstract

A series of bis(4-alkoxyphenyl) viologen bis(triflimide) salts with alkoxy chains of different lengths were synthesized by the metathesis reaction of respective bis(4-alkoxyphenyl) viologen dichloride salts, which were in turn prepared from the reaction of Zincke salt with the corresponding 4-n-alkoxyanilines, with lithium triflimide in methanol. Their chemical structures were characterized by 1H and 13C nuclear magnetic resonance spectra and elemental analysis. Their thermotropic liquid-crystalline (LC) properties were examined by differential scanning calorimetry, polarizing optical microscopy, and variable temperature X-ray diffraction. Salts with short length alkoxy chains had crystal-to-liquid transitions. Salts of intermediate length alkoxy chains showed both crystal-to-smectic A (SmA) transitions, Tms, and SmA-to-isotropic transitions, Tis. Those with longer length of alkoxy chains had relatively low Tms at which they formed the SmA phases that persisted up to the decomposition at high temperatures. As expected, all of them had excellent thermal stabilities in the temperature range of 330–370 °C. Their light-emitting properties in methanol were also included.

High Ionic Conductivities of Ionic Materials as Potential Electrolytes

“…In subsequent heating and cooling scans, there are no additional thermal events were visible for 1 and 2, suggesting that crystallisation of these samples must be a slow process. The absence of liquid crystal behaviour in these salts, contrasts with the recent report of smectic phases by analogous alkoxy-terminated (n ≥ 6) viologens (see Figure 8) [32] and others [36][37][38]. Even though comparable lengths of terminal chains would have been expected to promote microphase separation and smectic behaviour in 1-3, the formation of stronger interactions by the ethyleneoxy High Ionic Conductivities of Ionic Materials as Potential Electrolytes DOI: http://dx.doi.org/10.5772/intechopen.107949 [32].…”

“…The 4-oligoethyleneoxypheylanilines were prepared according to and 4,4′-bipyridine in acetonitrile on heating to reflux, to yield the so-called Zincke salts [30,31] (step 3); and (ii) subsequent anionic ring opening and ring closing reactions (ANROC) with the corresponding 4-oligoethyleneoxypheylanilines, in N,N-dimethylacetamide (DMAc) at room temperature (step 4). Lastly, P1-P3 were converted to 1-3 by metathesis with lithium triflimides in methanol [32] (step 5). Detailed synthetic procedures and analyses are also given elsewhere [33].…”

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

“…Most of the ILCs reported in the literature show SmA phases and some show both SmC and SmA phases of low order, due to nano-segregation of the polar ionic groups and nonpolar hydrophobic alkyl groups, and giving rise to layer structures in which hydrophobic layers alternate with ionic layers [26,32,57,58,64,65]. In rare instances, ILCs can also show SmB [8],…”

Viologen capped by nucleobase—building blocks for functional materials: synthesis and structure–properties relationship

“…In an ionic liquid crystalline matrix, viologens can be used as multistimuli chromic additives to construct ''task-specific'' materials [15][16][17]. Recent reports describing viologens capped by alkyl or alkoxy chains exhibit preferentially smectic mesophases [18][19][20]. Particularly, the mesogenic ionic complexes of polycationic viologens with anionic cunitic ligands such as 3,4,5tris(dodecyloxy)benzene sulfonate (DOBS -) were prepared in our group by phase transfer catalysis [16].…”