Nuclear magnetic resonance has been employed as a probe for the collective hydrocarbon chain dynamics in the organic inorganic model biomembranes (CnH2n+1NH3)(2)SnCl6, undergoing order-disorder and conformational phase transitions. No anomalies were observed in the laboratory-frame spin-lattice relaxation measurements at the order-disorder phase transitions, whereas a discontinuity was manifest at the conformational phase transitions characteristic of a first-order phase transition. On the other hand, our rotating frame spin-lattice relaxation measurements revealed a low-frequency critical collective chain dynamics in the kilohertz regime associated with the order-disorder phase transition. (c) 2005 Elsevier B.V. All rights reserved.