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Influence of the anions on the N-cationic benzethonium salts in the solid state and solution: Chloride, bromide, hydroxide and citrate hydrates
- Source :
- AIP Advances, Vol 6, Iss 6, Pp 065322-065322-24 (2016)
- Publication Year :
- 2016
- Publisher :
- AIP Publishing, 2016.
-
Abstract
- The crystal structures of the hydrated cationic surfactant benzethonium (Bzth) chloride, bromide, hydroxide, and citrate have been determined by X-ray diffraction analysis and compared with their structures in solution well above their critical micelle concentration. The differences in the nature of the various anions of the four Bzth-X materials lead to unique anion environments and 3-D molecular arrangements. The water molecule in the monoclinic Bzth-Cl or Bzth-Br forms is hydrogen bonded to the halides and particularly to the hydrogens of the methoxy groups of the Bzth moiety notwithstanding the weak Brønsted acidity of the methoxy hydrogens. The citrate strongly interacts with the hydrogens of the methoxy group forming an embedded anionic spherical cluster of a radius of 2.6 Å. The Bzth-OH crystallizes in a hexagonal lattice with two water molecules and reveals free water molecules forming hydrogen bonded channels through the Bzth-OH crystal along the c-axis. The distances between the cationic nitrogen and the halides are 4.04 Å and 4.20 Å, significantly longer than expected for typical van der Waals distances of 3.30 Å. The structures show weakly interacting, alternating apolar and polar layers, which run parallel to the crystallographic a-b planes or a-c planes. The Bzth-X salts were also examined in aqueous solution containing 20% (v/v) ethanol and 1.0 % (v/v) glycerol well above their critical micelle concentration by small-angle X-ray scattering (SAXS) and wide-angle X-ray scattering (WAXS). The [1,1,1] planes for the Bzth Cl or Br, the [0,0,2] and [1,1,0] planes for the Bzth-citrate, the [2,-1,0] planes and the [0,0,1] planes for the Bzth-OH found in the crystalline phase were also present in the solution phase, accordingly, the preservation of these phases are a strong indication of periodicity in the solution phase.
- Subjects :
- Aqueous solution
010304 chemical physics
Chemistry
Small-angle X-ray scattering
Hydrogen bond
Inorganic chemistry
General Physics and Astronomy
02 engineering and technology
Crystal structure
021001 nanoscience & nanotechnology
01 natural sciences
lcsh:QC1-999
chemistry.chemical_compound
Crystallography
Bromide
Critical micelle concentration
0103 physical sciences
Hydroxide
0210 nano-technology
lcsh:Physics
Monoclinic crystal system
Subjects
Details
- ISSN :
- 21583226
- Volume :
- 6
- Database :
- OpenAIRE
- Journal :
- AIP Advances
- Accession number :
- edsair.doi.dedup.....da5a5fc7d8ad7ec7edbf2e1c7ea6a948
- Full Text :
- https://doi.org/10.1063/1.4954882