Structure of mono-acid even-numbered β-triacylglycerols

Abstract

The crystal structure of the β polymorph of tripalmitin (1,2,3-trihexadecanoylglycerol, β-PPP) has been determined by single-crystal X-ray diffraction. The molecules crystallize in space group P1¯ in an asymmetric tuning-fork conformation. This structure and the already-known crystal structures of β-tricaprin (β-CCC) and β-trilaurin (β-LLL) could be matched in an overlap model. Apart from a difference in chain length, the three structures are almost identical. The overlap model can be used to predict the crystal structure of the other members of the C n C n C n -type (n = even) TAG series reasonably accurately. This is demonstrated by predicting the crystal structure for β-trimyristin (β-MMM) and successively comparing the experimental and calculated X-ray powder diagrams.