Induction of ionic smectic C phases: a systematic study of alkyl-linked guanidinium-based liquid crystals

Abstract

All chemicals were, unless stated otherwise, provided by the supplier and used without further purification. Dry solvents were dried by conventional laboratory methods. The eluents for chromatography petroleum ether (low-boiling) and ethyl acetate were distilled prior to use.For thinlayer chromatography silica gel 60 F254 glass plates with a layer thickness of 0.25 mm on aluminium (pore size 60 Å) from the company Merck were used. Column chromatography was performed using silica gel with a particle diameter of 40 -60 µm from the company Fluka.1 H NMR spectra were measured using the Bruker Avance 300 and Bruker Avance 500 spectrometers at 300 MHz and 500 MHz, respectively and 13 C-NMR spectra at 75 MHz and 126 MHz, respectively. Deuterated chloroform (CDCl3) and deuterated dimethyl sulfoxide (DMSO-d6) were used as solvents. The chemical shift δ in ppm (parts per million) refers to the standard tetramethylsilane. The numbering of atoms can be different from the IUPAC nomenclature in order to ensure better comparison of various compounds. In order to assign the signals of the 1 H and 13 C NMR spectra, COSY, HSQC and HMBC measurements were carried out.

Columnar Propeller‐Like 1,3,5‐Triphenylbenzenes: Probing the Effect of Chlorine on the Suzuki Cross‐Coupling and Liquid Crystalline Properties

“…In the case of boronate 6d , the WAXS profile displayed a sharp (10) reflection and a diffuse halo (Figure S6a). Decreasing layer distances with increasing temperatures (Figure S6b) as well as the texture confirmed the proposed SmA phase . Because of a similar structure and layer thickness as compared to known MIDA‐boronates, a bilayer packing (SmA d ) was suggested.…”

Fluorenone imidazolium salts as novel de Vries materials

“…[1][2][3][4][5][6][7][8] The strong tendency of ILCs to nanosegregate ionic and non-charged segments during liquid crystalline self-assembly leads to a strong preference of the non-tilted SmA phase as their archetypal mesophase, while for example the tilted SmC phase is much less common among ILCs. [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.…”

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

“…Williamson etherification of the known ω‐bromo‐alkyl‐ N ‐phthalimides 2 provided the azobenzene derivatives 3(C n ) with terminal N ‐phthalimido‐protecting group. Subsequent hydrazinolysis followed by reaction with tetramethylformamidinium chloride and triethylamine according to the method by Kantlehner and treatment with HCl or HBr (method A) yielded the guanidinium chlorides Gua(C n )Cl (n = 4, 6, 8) and bromides Gua(C n )Br (n = 4, 8), respectively, in 42 to 56%.…”

“…However, general design principles for SmC promoting mesogens are unknown for ILCs in contrast to the guidelines successfully developed by Lemieux for noncharged liquid crystals . From our previous findings that alkoxybiphenyls with tethered guanidinium moiety displayed indeed SmC phases in addition to the SmA phase, when the spacer was sufficiently long, we concluded that the connection of the cationic head group with a rigid calamitic unit via a flexible tether seems to be a promising design motive for that purpose. In addition, Westphal and we independently disclosed that azobenzenes tethered to imidazolium head groups formed tilted mesophases.…”