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2,2'-Dotriacontanedioylbis(1-palmitoyl-sn-glycero-3-phosphocholine ) was synthesized chemically as a dimeric version of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine. Upon sonication in water, the bipolar lipid furnished a planar membrane of about 50 Angstrom thickness with gel-to-liquid crystalline phase transition constants of Tm = 53.4 degrees C, DeltaH = 20.9 kcal/mol, and DeltaS = 64.0 e.u. In an air/water interface, the lipid displayed unique surface pressure-surface area isotherms with a limiting area of 105-190 Angstrom/molecule at 10-20 degrees C. The lipid was a substrate of phospholipase A2 (Naja mocambique), which afforded 1-palmitoyl-sn-glycero-3-phosphocholine and dotriacontanedioic acid as final products.

1,2-Bis(dihydrophytyl)glycero-3-phosphate (DPhyPA) was synthesized as an analog of archaebacterial lipids. Upon sonicating in amine-containing buffers like 0.05 M Tris–HCl (pH 7.8), the lipid gave rise to the stable liposomal assemblies, which could store 5(6)-carboxyfluorescein at high temperature as high as 70 °C in the interior. The assembly also had a large negative zeta-potential and showed an absence of gel-to-liquid crystalline phase transition from −20 to 80 °C. A Langmuir monolayer at an air/water interface suggested that the maximum molecular area of the lipid was 0.9—1.0 nm2. These properties were compared with the assemblies prepared from conventional 1,2-dipalmitoyl-sn-glycero-3-phosphate and 1,2-dipalmitoyl-sn-glycero-3-phosphocholine.

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