PROPERTIES OF UNUSUAL PHOSPHOLIPIDS .1. SYNTHESIS, MONOLAYER INVESTIGATIONS AND CALORIMETRY OF DIACYLGLYCEROPHOSPHOCHOLINES CONTAINING MONOACETYLENIC ACYL CHAINS

Isomeric diacylglycerophosphocholines containing various octadecynoic acids (4-, 6-, 9-, 12-, 14- and 17-octadecynoic acid) were synthesized and purified to homogeneity. Their behaviour in monolayers, when stud ied by the Langmuir-Blodgett film balance technique, revealed systemat ic relationships between structure and packing properties. The thermot ropic phase behaviour of these novel phospholipids, as measured by dif ferential scanning calorimetry, depended in a systematic fashion on th e position of the triple bond: the gel-to-liquid-crystalline phase tra nsition temperature (T-m) passed through a minimum of -3.4 degrees C f or a triple bond in position 9.