Structural investigations of β′ triacylglycerols: An x‐ray diffraction and microscopic study of twinned β′ crystals

To reveal the structure ofβ′ triacylglycerols in detail, LML (C12C14C12) was purified by a zone‐melting procedure, and twinned crystals ofβ′ stable LML were obtained from a melt,β′ LML crystallizes in the monoclinic space group C2, with eight molecules in the unit cell. A powder X‐ray diffraction study of solid compounds of 1:1 mixtures of selected triacylglycerols led to the conclusion that the triacylglycerol molecules in theβ modification have a 1,2 chair‐conformation (i.e., the fatty acid chains on glycerol positions 1 and 2 are adjacent, with the chain on the 3‐position forming the back rest of the chair). Packing studies and the positions of two‐fold axes and two‐fold screw axes in the unit cell require that the molecules are bent at the glycerol site. The fatty acid chains make an angle of 25° with the long axis of the unit cell. Electron micrographs and precession photographs indicate that the twinning results from the stacking of a large number of thin crystalline platelets in two distinct orientations.