NMR study of distinct phase transitional behaviors in (C _nH _2n+1NH ₃) ₂SnCl ₆

Phase transitions in bis-(n-C _nH _2n+1NH ₃) ₂SnCl ₆, where the hydrocarbon part is analogous to lipid membrane, were investigated by means of 200-MHz ¹H nuclear magnetic resonance. As a result, critical fluctuations and molecular dynamics associated with the phase transitions, an order-disorder and a conformational phase transition, were distinguished in a wide temperature range. The critical dynamics, observed in the long-chain compounds but not in the short-chain compounds by laboratory frame spin-lattice relaxation measurements, is discussed in view of the chain length dependence of molecular dynamics.