Sorption and selective properties of binary liquid-crystalline sorbent based on 4-Methoxy-4′-ethoxyazoxybenzene and a cetylated β-Cyclodextrin

Abstract

The mesomorphous, sorption, and selective properties of a binary sorbent based on achiral liquid crystal 4 methoxy 4' ethoxyazoxybenzene and macrocyclic heptakis(2,3,6 tri O acetyl) β cyclodextrin (10.25 wt %) are investigated. Macrocyclic additive was found to induce the formation of a helically twisted nematic phase (N*). The standard and excess thermodynamic functions of sorption by binary sorbent from gaseous phase are determined for 29 organic compounds (n alkanes, cycloalkanes, arenes, monoatomic alco hols, heterocycles, optical isomers of camphene, limonene, and butanediol 2,3). The investigated sorbent is found to have high structural selectivity over the wide temperature range of the N* mesophase (α p/m = 1.11-1.06, 95-120°C) and moderately expressed enantioselectivity within the narrow region of transition from the solid crystalline state to the N* mesophase (α +/-= 1.024-1.088, 91-100°C).

Complexes of peracetylated cyclodextrin in a non-aqueous aprotic medium: the role of residual water

“…Some enantioseparations, both on analytical and preparative scales, [24][25][26][27][28] have also been published and a couple of solid complexes have been prepared using various techniques. [29][30][31] The investigation of soluble complexes in solution, particularly in apolar solvents, is rare and only a few examples are available in technical papers. 4,19,24,32 Guest molecules in those cases also carry some polar components, apart from a species studied in a recent analytical impacted publication by Kopytin et al 22 The effect of aCD peracylation on its molecular structure has been investigated using single crystal X-ray analysis, 3 and only revealed the presence of at least two associated water molecules in the solid state, despite the crystalline complex being prepared from aqueous 2-propanol.…”

Surface Properties of Gas Chromatographic Adsorbents Based on Silochrome S-80 Modified by Transition Metal 8-Oxyquinolinates

“…The error in the experimental determination of the specific retention volume ( , cm 3 /g) did not exceed 4.5%; the values of differential molar heat of adsorption ( , kJ/mol) and changes in the entropy of adsorption ( , J/(mol K)) did not exceed 2.9 kJ/mol and 7.0 J/(mol K), respectively. The contribution of 8hydroxyquinolinate modifiers to adsorbate retention (δ, %) was estimated according to the procedure in [14] using the specific retention volumes for columns with modified and initial Silochrome S-80.…”

Isomer-Selective Properties of Carbon Adsorbent Modified by "4-n-octyloxy-4'-cyanobiphenyl – β-Cyclodextrin" under Gas-Adsorption Chromatography Conditions

“…Separation and detection of isomers is the most complex task of the modern day analytical chromatography that is important for organic chemistry, biochemistry, chemical, pharmaceutical and biotechnological industries. One of the methods for obtaining universal isomer-selective sorbents (stationary phases) in gas-liquid chromatography is the use of binary systems based on achiral liquid crystals (LC) and cyclodextrins (CD) [1][2][3]. The LC matrix of such stationary phases facilitates the separation of structural isomers, while the cyclodextrins dissolved in it facilitate the separation of optical isomers due to the difference in the stability of the sorbate-macrocycle binding complexes.…”