New evidence for β′‐2 p.p+2.p triacylglycerol crystal structure

Abstract

In a recent paper (1) we proposed a crystal structure for the homologously isomorphous β′-2 p.p+2.p triacylglycerol series. Another recent paper (2), by different authors, contains three X-ray powder diffraction (XRPD) patterns that confirm the correctness of our proposed structure. Unfortunately, only one of these XRPD patterns was available to us when submitting our paper (1). Figure 1 shows the published experimental XRPD patterns. Figure 2 shows the XRPD patterns calculated from our proposed structure. The alternating intensities of the first three experimental patterns in region A (31l reflections with l = 4, 6, 8, or 10) and peak B (the 600 reflection) are very well reproduced by our structure. In our opinion, the fourth experimental pattern does not correspond to a β′ polymorph. Peak C at d = 4.57 A, i.e., at 2θ = 19.4° (see Table 1 in Ref. 2) indicates that this is a β polymorph, which has been described for this compound by DeJong (3), among others. This explains why the XRPD pattern calculated from our β′ structure does not match the experimental pattern. New Evidence for β′-2 p.p+2.p Triacylglycerol Crystal Structure