N-decylammonium chloride is a polymorphic solid which exhibits a variety of layered phases. The molecular dynamics and phase transitions in these phases have been studied using2H NMR of selectively deuterated n-decylammonium in the chain positions 1 and 6 and in the ammonium group. Measurements were performed over the temperature range of the interdigitated phase I, the non-interdigitated monoclinic phase δ, the tetragonal phase α, and the monotropic phase e, obtained upon cooling the sample from the α-phase. In phase I, below 321 K, the hydrocarbon chain is rigid except for ND3 rotation about its own symmetry axis. In phase δ, between 321 K and 325 K, a fast motion of the hydrocarbon chains is assigned to an exchange between two pairwise nonequivalent positions. The chains are slightly tilted in this phase. In phase α above 325 K the chains rotate freely around their long axes experiencing additional transgauche conformational dynamics. In the non-interdigitated phase e the spectra can be interpreted by assuming a reorientation between two variously occupied potential wells about the axis determined by the C-N bond, which is believed to be parallel to the normal bilayer axis.

Chain dynamics of bilayer n-decylammonium chloride studied by deuteron NMR spectroscopy

The results of a detailed DSC, X-ray powder diffraction and NMR investigation of n-decylammonium chloride (C10H21NH3Cl) are reported. If a sample in the interdigitated I phase is heated, it transforms to the non-interdigitated δ phase at ∼328K and then to the β and α phase at ∼334K. On cooling the transitions to the β and δ phases occur at ∼322K and 319K, respectively, but instead of returning to the I phase, the sample transforms to the ϵ phase at ∼297K. The ϵ phase is metastable, but becomes stable below ∼210K. If the sample is heated from a temperature below 210K, it shows a transition to the ϵ′ phase at ∼288K and then to the δ, β and α phases. A sample heated from the metastable ϵ phase does not show the transition to the ϵ′ phase, but exhibits an exothermic transition at ∼274K. In the ϵ phase the intensity of diffraction peaks are relatively weak due to a disordered lattice. If the temperature is lowered from the δ → ϵ transition temperature the relatively large expansion coefficient of the a cell di...

The structure and molecular dynamics of solid n-decylammonium chloride

We have carried out a 1H nuclear magnetic resonance line shape analysis near the irreversible interdigitated-to-noninterdigitated chain configurational phase transition in decylammonium chloride (C10H21NH3Cl), a model biomembrane. The splitting parameter corresponding to the nematic order of the hydrocarbon chain shows a two-dimensional Ising behavior and indicates a chain defect motion in addition to the chain reorientational motion. The origin of the low-frequency critical fluctuation is attributed to a critical slowing down of the collective gear-like reorientation of the rigid hydrocarbon chain.

Critical chain dynamics near the interdigitated–noninterdigitated chain configurational phase transition in decylammonium chloride

Characterization and coordination of intercalation - Non-intercalation phase transition in a new hybrid halide perovskite (n-C 16 H 33 NH 3 ) 2 ZnCl 4

Proton nuclear magnetic resonance (NMR) relaxation measurements were carried out to investigate the low-frequency hydrocarbon chain dynamics in decylammonium chloride (C 10 H 21 NH 3 Cl), a model biomembrane undergoing an irreversible structural phase transition. It is demonstrated by systematic proton NMR study of spin-spin relaxation and rotating frame spin-lattice relaxation that a low-frequency chain dynamics is responsible for the critical dynamics associated only with the interdigitated-to-noninterdigitated chain configurational phase transition.

Low-Frequency Chain Dynamics in Decylammonium Chloride

The structural phase transitions between the intercalated and the non-intercalated phases of the layer structure compound n-decylammoniumchloride and n-hexylammoniumchloride have been studied via proton-14N and proton-35Cl nuclear quadrupole double resonance. The results have been related to an order-disorder model of the alkylammonium chains. The temperature dependence of the order parameters of the −NH3 head groups has been determined.

H. Arend

Papers

14N and35Cl nuclear quadrupole double resonance study of the phase transitions in n-decylammoniumchloride and n-hexylammoniumchloride

Nitrogen-14 and chlorine-35 double resonance study of the phase transition in the intercalated bilayer compound n-decylammonium chloride