The bilayer compounds[n-CnH2n+1N(CH3)3]2Zn Cl4(n=16,18)experience solid-solid phase transition within the temperature range of 310 to 340 K.The low-temperature crystal structures of the pure compounds are characteristic of the piling effect in which a 2D macro-anion Zn Cl42- is sandwiched between two alkylammonium layers.These layers become conformationally disordered in the high-temperature phases.The structures can alternatively be viewed as a double layer of alkylammonium ions between Zn Cl42- sheets and can be considered as crystalline models of lipid bilayers.The experimental subsolidus binary phase diagram of[n-C16H33N(CH3)3]2Zn Cl4-[n-C18H37N(CH3)3]2Zn Cl4 has also been established over the whole composition range by differential scanning calorimetry(DSC)and X-ray diffraction.In the phase diagram,one intermediate compound[n-C16H33N(CH3)3][n-C18H37N(CH3)3]Zn Cl4 at WC16C3Zn%47.50 and two eutectoid invariants points at WC16C3Zn%35.10 and75.70 were observed;the respective temperatures of the two eutectoids are 320±1 and 315±1 K.In addition,there are three noticeable solid solution ranges in the phase diagram:α-phase at the left,β-phase at the right,andγ-phase in the middle. The bilayer compounds [n-CnH2n + 1N (CH3) 3] 2Zn Cl4 (n = 16,18) experience solid-solid phase transitions within the temperature range of 310 to 340 K. The low-temperature crystal structures of the pure compounds are characteristic of the piling effect in which a 2D macro-anion Zn Cl42- is sandwiched between two alkylammonium layers. These layers become conformationally disordered in the high-temperature phases. structures can alternatively be viewed as a double layer of alkylammonium ions between Zn Cl42 - sheets and can be considered as crystalline models of lipid bilayers. The experimental subsolidus binary phase diagram of [n-C16H33N (CH3) 3] 2ZnCl4- [n-C18H37N (CH3) 3] 2ZnCl4 has also been established over the whole composition range by differential scanning calorimetry (DSC) and X-ray diffraction in the phase diagram, one intermediate compound [n-C16H33N (CH3) 3] [n- C18H37N (CH3) 3] Zn Cl4 at WC16C3Zn% 47.50 and two eutectoids invariants points at WC16C3Zn% 35.10 and75.70 were observed; the respective temperatu res of the two eutectoids are 320 ± 1 and 315 ± 1 K. In addition, there are three noticeable solid solution ranges in the phase diagram: α-phase at the left, β-phase at the right, and γ-phase in the middle .