INFLUENCE OF ALPHA-BRANCHED FATTY-ACID CHAINS ON THE THERMOTROPIC BEHAVIOR OF RACEMIC 1-O-HEXADECYL-2-ACYL-GLYCERO-3-PHOSPHOCHOLINES

Phosphatidylcholines containing an alpha-branched palmitic acid ester linked to position C2 of the glycerol backbone were synthesized and characterized using differential scanning calorimetry and X-ray diffraction, As the length of the sidegroup substituted on the palmitic acid chain is changed, the calorimetric parameters pass through a minimum. The polymorphic behaviour is different when the sidegroup is larger, or smaller, than propyl. The comparison of the physicochemical parameters of isomers differing in the bonding of the branched chain fatty acid to the glycerol backbone (to position C1 or C2, respectively) shows that the chains are nonequivalent.