Structure of mono-acid even-numbered β-triacylglycerols

The crystal structure of the beta polymorph of tripalmitin (1,2,3-trihexadecanoylglycerol, beta-PFP) has been determined by single-crystal X-ray diffraction. The molecules crystallize in space group P (1) over bar in an asymmetric tuning-fork conformation. This structure and the already known crystal structures of beta-tricaprin (beta-CCC) and beta-trilaurin (beta-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 CnCnCn-type (n = even) TAG series reasonably accurately. This is demonstrated by predicting the crystal structure for beta-trimyristin (beta-MMM) and successively comparing the experimental and calculated X-ray powder diagrams.