Anion-induced ionic liquid crystals of diphenylviologens

Abstract

Two series of ionic liquid crystals derived from diphenylviologens, 1 and 2, were prepared and their photophysical and electrochemical properties were also investigated.

Recent synthetic advances in pyridine-based thermotropic mesogens

“…Also, they obtained similar results when the experiments were performed even at 60 C and 30 C. Hence, these complexes can be utilized in photonics. Wang et al 59 prepared two series of ionic liquid crystals from diphenylviologens. Further, they synthesized the precursors diphenyl viologen dichloride 133 and di(4-alkoxyphenyl) viologen dichlorides 134a-c (R ¼ C n H 2n+1 , n ¼ 10, 12,14) through Zincke reactions by referring to previous literature reports by Nanasawa et al 60 and Kuo et al 48 During the metathesis of counter anions, methanol was used as the phase transfer atmosphere.…”

Mono- and Di-Quaternized 4,4′-Bipyridine Derivatives as Key Building Blocks for Medium- and Environment-Responsive Compounds and Materials

“…The viologens employed, encompassing oligoether N,N′ substituents (in a similar fashion as in the prototype ILC 60 by Tabushi [98]) exhibit medium-responsiveness, as well as charge-transfer-complex formation aptitude. Wang et al also reported a family of diphenyl-viologens (67,68, Figure 27) and investigated their ILCs employing a variety of anions [102]. Parallel to the interesting electrochemical properties, these ILCs found to exhibit solvatochromism.…”

“…Interestingly, even though the MeOH or CH2Cl2 solutions of 68 exhibited no photoluminescence, they were found to emit light when dissolved in aqueous mixtures, especially at high water fractions (λem = 463 to 529 nm strongly depending on the counter anion). This effect was attributed to the aggregation occurring primarily in water-rich mixtures [102]. More recently, a multi-functional ILC material with aptitude to form bicontinuous cubic phases, based on a zwitterionic viologen was developed by Kobayashi and Ichikawa [103].…”

Thermotropic Liquid-Crystalline Properties of Viologens Containing 4-n-alkylbenzenesulfonates

“…These applications, to name a few, include electrochromic devices, molecular machines, organic batteries, and carbohydrate oxidation catalysts in alkaline fuel cells [2,3]. In addition, they were studied not only for the preparation of the ever-increasing class of ionic liquids with proper chemical modifications of cations and anions [4][5][6][7][8][9][10][11][12], but also for the preparation of ionic liquid crystals (ILCs) [7,[13][14][15][16][17][18][19][20][21][22][23][24]. To mention several their chemical structures (I-VI) are given in Figure 1 as representative examples.…”

“…Their LC phases are found to be dependent on both the chemical architecture of viologen moieties including dialkyl [13,[17][18][19]23], asymmetric dialkyl [7], di(oligooxyethylene) [14,15], di(3,4,5-tri-n-alkoxybenbenzyl) [22], diphenyl [16,24], and 4-n-alkoxyldiphenyl [24], and the chemical architecture of the anions are of varying sizes. The anions to date include bromide, iodide [14,15], − BF 4 , − PF 6 [22,24], − OTf, − SCN, − NTf 2 , 4-n-alkylsulfonates [24], 4-n-alkylbenzenesulfonates [16], and 3,4,5-tri-n-dodecyloxybenzenesulfonate [23]. Recently, their use in energy-related systems stemming from the unique properties of redox properties as well as LC properties of viologen moieties has given the boost for the exploration of this class of materials.…”