Critical dynamics in layer-structured (C18H37

Distinct critical fluctuations and molecular motions manifest in a model biomembrane

“…In C10Sn as in well as C12Sn, the critical fluctuations were not reflected in the spin-lattice relaxation [6,7], but were observed in C18Sn near the order-disorder transition temperature [4,5]. In C18Sn, the spin-lattice relaxation pattern near the order-disorder transition temperature depends on the Larmor frequency.…”

“…In C18Sn, the spin-lattice relaxation pattern near the order-disorder transition temperature depends on the Larmor frequency. At 200 MHz, the spin-lattice relaxation pattern is a double-exponential form, for which the shorter time constant only reflects a critical fluctuation near the order-disorder transition temperature [4]. The spin-lattice relaxation is a single-exponential form at 45 MHz, where the time constant also shows a divergent anomaly near the order-disorder transition temperature [5].…”

“…In our previous 1 H NMR studies of the CnSn systems, two typical successive phase transitions were observed [4][5][6][7]: (a) order-disorder transition of the rigid alkyl chains accompanied by a uniaxial reorientation about their long axes along with the flipping of the polar groups, such as NH 3 , between the potential wells, and (b) conformational transition leading to a partial melting of the alkyl chain part. In the low temperature (LT) phase below the order-disorder transition temperature, the alkyl chains are rigid and adopt an all-trans conformation.…”

“…In a 2 H NMR study of C4Cd [17], the evolution of orientational and conformational orders of the hydrocarbon chain was shown to be similar to those in lipid membranes, although the order parameter tensor was not uniaxial and the value in the high temperature phase was two times greater than that in the L a phase. Critical fluctuations have been observed in a few studies near the order-disorder transition temperature of a lipid layer intercalated between the inorganic layers [4,5,21]. In hydrated lipid membranes, (pseudo)critical swelling has been intensively studied near the main transition temperature, mostly near the L a 4P b transition temperature [22][23][24], and much less frequently, near the L a 4P b transition temperature [25].…”

“…In contrast to the case of bis-n-alkylammonium tetrachlorometallates (n-C n H 2nC1 NH 3 ) 2 MCl 4 with MZCd, Cu, Mn and Zn (CnM) [13][14][15][16][17], little information is available on the phase transitions in CnSn [4][5][6][7][18][19][20]. The first systematic studies on the layer structure intercalation compounds including C10Cd were made by Blinc and coworkers using magnetic resonance.…”