Temperature-dependent IR spectroscopic and structural study of 18-crown-6 chelating ligand in the complexation with sodium surfactant salts and potassium picrate

Abstract

Abstract18-crown-6 ether (18C6) complexes with the following anionic surfactants: sodium ndodecylsulfate (18C6-NaDS), sodium 4-(1-pentylheptyl)benzenesulfonate (18C6-NaDBS); and potassium picrate (18C6-KP) were synthesized and studied in terms of their thermal and structural

18-Crown-6–Sodium Cholate Complex: Thermochemistry, Structure, and Stability

“…42 It seems that in this case, the arrangement in the triclinic phase also appears as layer like, with crown ether unit and sodium on one side, and the cholate anion on the other side, similar as found for 18C6-sodium 4-(1-pentylheptyl)benzenesulfonate. 56 Unlike these results, the crystal smectic phase layers of 18C6-sodium n-dodecylsulfate are composed of repetitive units of two crown ether layers with extended dodecyl chains. 56 For the two monoclinic phases (Figure 6 and 7), the fact that there exists a unique axis requires it being a 2-fold axis, so the space group can only be assigned as P2.…”

“…56 Unlike these results, the crystal smectic phase layers of 18C6-sodium n-dodecylsulfate are composed of repetitive units of two crown ether layers with extended dodecyl chains. 56 For the two monoclinic phases (Figure 6 and 7), the fact that there exists a unique axis requires it being a 2-fold axis, so the space group can only be assigned as P2. In addition, as there is only one molecule in the unit cell and the molecule itself do not have a 2-fold rotational axis, we propose that the 2-fold symmetry originate from the molecules taking randomly one of the two different configurations, so called "orientational disorder" (related by a 2fold symmetry) in the unit cell.…”

“…56 The formation of liquid crystalline phases is very common in complexes with crown ethers, but unlike the examined one, most of the mesophases formed are stable until isotropisation and are enantiotropic. [45][46][47][48][49][50][51] Unlike chiral nematic behavior noticed in the examined complex, smectic phases were obtained for other 18C6 complexes, 56 hexagonal columnar mesophases are formed in gallic acid substituted ortho-terphenyl dimers linked by a central 18C6 ether 40 or dibenzo 18C6 with different alkyl chain lengths, 46 and nematic liquid crystals as well as smectic A phase in combination of 18C6 or rodlike 4,4" didecyloxyp-terphenyl unit. 56 The diversity in thermal and thermotropic behavior of 18C6 complexes points to the promoting effect of the attached groups or guest molecules in the complex.…”

“…Thus, some phase transitions, overlooked by more commonly used methods, become readily evident by IR spectroscopy, as seen in our recent publications. 56,57 Further advantage of temperature-dependent IR spectroscopy lies in the fact that it provides an elegant link between macroscopic and microscopic properties. In other words, it does not only detect phase transitions, but the variations in the fingerprint region of the recorded spectra reflect the changes at molecular level, which are manifested at macroscopic level as phase transitions.…”

Polyfunctional Nanosystems on Amphiphilic and Hybrid Platform: Self-Assembly, Mesogenic Properties and Application

“…Чем меньше различие между геометрическими размерами катионов и полости макроциклов, тем выше устойчивость образующихся при связывании ионов металлокомплексов. Примером макроциклических лигандов, комплексующих ионы металлов для создания ЖК, могут служить порфириновые производные [137][138][139] и краун-эфиры [140][141][142]. Причем в качестве мезогенов могут быть задействованы как алкилированные производные макроциклов, так и суперамфифильные комплексы макроцикл-ПАВ.…”