Hunting for smectic C in calamitic azobenzene ionic liquid crystals with different cationic head groups

Abstract

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Fluorenone imidazolium salts as novel de Vries materials

“…[12][13][14][15][16] We have previously identied ILCs 1, 2 showing rare SmC phases (Scheme 1), which consist of a calamitic core unit carrying one side chain and a exible spacer connected to a cationic head group. [15][16][17][18] Upon examination of the order parameter of the SmA phase of these compounds it was found that the long range orientational order (S 2 ) in the SmA phase was much smaller as compared to the values obtained for SmA phases from non-ionic liquid crystals. [19][20][21][22] On the other hand, the 1D translational order (smectic order parameter 3) of the SmA phase of ILCs is much larger 17,18 as compared to non-ionic SmA phases.…”

“…[15][16][17][18] Upon examination of the order parameter of the SmA phase of these compounds it was found that the long range orientational order (S 2 ) in the SmA phase was much smaller as compared to the values obtained for SmA phases from non-ionic liquid crystals. [19][20][21][22] On the other hand, the 1D translational order (smectic order parameter 3) of the SmA phase of ILCs is much larger 17,18 as compared to non-ionic SmA phases. [23][24][25][26] Thus ILCs possess a high lamellar order but only a low long range orientational order as compared to neutral liquid crystals and in that respect behave similar to the so called de Vries materials.…”

“…This trend is in agreement with previous observations on azobenzene ILCs. 17 It should be noted that the behaviour of ILCs consisting of cationic group-spacer-mesogenic core-side chain is more complex as compared to ILCs containing side chain-cationic group-side chain.…”

“…[75][76][77][78][79][80] As mentioned above, in contrast to neutral calamitic liquid crystals ILCs are rather reluctant to form SmC phases. Despite the few known examples, [12][13][14][15][16][17][18] it is still an ongoing challenge to develop design principles for ILCs displaying both SmA and SmC phases. Moreover, ILCs with de Vries properties should provide a general insight into the driving forces for layer contraction and layer tilting of ionic mesogens and thus are relevant for electro-optic devices.…”

Self‐Assembly of Aminocyclopropenium Salts: En Route to Deltic Ionic Liquid Crystals

“…[43] Indeed, guanidinium ions are known building blocks that support mesomorphism of ionic liquid crystals (ILCs). [44][45][46][47] ILCs are anisotropic fluids with long-range orientational order caused by Coulombic interactions between cationic headgroups and counterions,nanosegregation between immiscible parts (that is,a ni onic headgroup,r igid core,a nd lipophilic tail), minimization of free volume complemented by van der Waals interactions, p-p,a nd hydrogen bonding interactions. [44,45] As ILCs have been reported to serve as al ink between neutral liquid crystals and polyelectrolytes, [48] insight into the structure-property relationships of aminocyclopropenium-derived ILCs should enable better tuning of the corresponding polyelectrolytes carrying aminocyclopropenium units for both batteries and fuel cells, [27][28][29][30][31][32]49,50] as well as gene-delivery vectors [51,52] (Figure 1).…”