Crystal Structure and Phase Transition Behavior of Dioctadecyldimethylammonium Chloride Monohydrate

Abstract

Monohydrated single crystals of dioctadecyldimethylammonium chloride (DC 18 DA + Cl − ·H 2 O) were prepared and the crystal structure was determined to elucidate the effects of water molecules on the crystalline to liquid-crystalline phase transition behavior. From the observation during the phase transition of as-prepared single crystals by polarizing optical microscopy and powder X-ray diffractometry, we demonstrated that the water molecules are firstly melted with increasing temperature and one-dimensional ionic chains, [-{Cl (1 1 -5) planes. This rearrangement is accompanied by the formation of a smectic A like bilayer structure. In addition, the one-dimensional ionic chains are simultaneously stretched to the chain direction, and alkyl chains are interdigitated to reduce a free space within the hydrophobic unit. are merged into two-dimensional ionic layers by sliding on the

Imidazolium-based ionic liquids with different fatty acid anions: phase behavior, electronic structure and ionic conductivity investigation

“…It also showed a peak at high angle (2y = 21.41) due to ordered orientation of alkyl chains. 39 For IL2, we observed sharp equidistance peaks, appearing at (2y = 2.721, 5.451, 8.171, 10.91) which corresponds to a d-spacing value of 3.24 nm. For both IL1 and IL2, the layer spacings are longer than the length of the ionic liquid molecule (see Table S2 of ESI, † estimated by the MOPAC AM1 method, CS Chem Office) but smaller than twice of its length.…”

“…14,21 No high angle diffraction peaks for molten alkyl chain were obtained due to disordering and shrinkage of the alkyl chain for thermal fluctuation. 39 On the other hand, IL1a was crystalline at room temperature. Therefore, we observed peaks at low angle regions at 2y = 5.831, 6.971, 10.11 and 10.51.…”

From Polymerizable Ionic Liquids to Poly(ionic liquid)s: Structure-Dependent Thermal, Crystalline, Conductivity, and Solution Thermoresponsive Behaviors

“…It should be noted that the d -spacing values for second peaks of [C 2( n =7–11) vim]­[Br]­s were higher in comparison to those of peaks for each sample of [C 2( n =7–11) vim]­[NTf 2 ], which is obvious considering the bulky size of the NTf 2 – ion. However, the evaluation of the nature of crystal packing from the wide-angle PXRD data was very complex, maybe due to the formation of a bilayer structure of the cationic alkyl chain . Therefore, from XRD analyses, it can be assumed that the alkyl chain-substituted imidazolium cations and Br – or NTf 2 – anions of these ILMs assembled in an interdigitated bilayer structure .…”

“…However, the evaluation of the nature of crystal packing from the wide-angle PXRD data was very complex, maybe due to the formation of a bilayer structure of the cationic alkyl chain. 76 Therefore, from XRD analyses, it can be assumed that the alkyl chain-substituted imidazolium cations and Br − or NTf 2 − anions of these ILMs assembled in an interdigitated bilayer structure. 64 Within the bilayer unit, the constituent ions are arranged through intermolecular alkyl chain−chain hydrophobic interactions and electrostatic interactions.…”

Ionic Liquid Crystals: Versatile Materials

“…(i) In some cases 490,539 In the SmA phase, the degree of undulation decreases with increasing temperature. This was attributed to dipolar interactions and possibly hydrogen-bonding interactions between the polar tails and the imidazolium cations (supported by molecular modeling and by the observation of the large extent of interdigitation of the oligo(ethylene oxide) chains by PXRD; see also section 4.2).…”