Structure of C _n C _n+2C _n -type (n = even) β′-triacylglycerols

Abstract

The crystal structures of the β′ phase of CLC (1,3-didecanoyl-2-dodecanoylglycerol) and MPM (1,3-ditetradecanoyl-2-hexadecanoylglycerol) have been determined from single-crystal X-ray diffraction and high-resolution X-ray powder diffraction data, respectively. Both these crystals are orthorhombic with space group Iba 2 and Z = 8. The unit-cell parameters of β′-CLC are a = 57.368 (6), b = 22.783 (2) and c = 5.6945 (6) Å and the final R value is 0.175. The unit-cell parameters of β′-MPM are a = 76.21 (4), b = 22.63 (1) and c = 5.673 (2) Å and the final R p value is 0.057. Both the β′-CLC and β′-MPM molecules are crystallized in a chair conformation, having a bend at the glycerol moiety. The zigzag planes of the acyl chains are orthogonally packed, as is typical for a β′ phase. Furthermore, unit-cell parameters of some other members of the C n C n +2 C n -type triacylglycerol series have been refined on their high-resolution X-ray powder diffraction pattern. Finally, the crystal structures are compared with the currently known structures and models of triacylglycerols.