Acta Crystallographica Section B

Structural Science

Volume 64, Part 2 (April 2008)

research papers

Acta Cryst. (2008). B64, 240-248 [ doi:10.1107/S0108768108004813 ]

Structures of mono-unsaturated triacylglycerols. III. The -2 polymorphs of trans-mono-unsaturated triacylglycerols and related fully saturated triacylglycerols

J. B. van Mechelen, R. Peschar and H. Schenk

Abstract: The [beta] -2 crystal structures of a series of saturated and trans-mono-unsaturated triacylglycerols (TAGs) have been solved from high-resolution powder synchrotron diffraction data. The series comprises symmetric as well as asymmetric even-numbered TAGs and the trans-mono-unsaturated ones all have a single elaidoyl chain. The structures have been solved with the direct-space parallel-tempering program FOX and refined with the Rietveld program GSAS. The [beta] -2 structures all crystallized in the space group $P\bar 1$ with the same molecular conformation. Within the resolution of the data no significant difference in packing or conformation is observed between trans-mono-unsaturated TAGs and saturated (stearoyl or palmitoyl) chain-containing analogues, in spite of the lower melting points of the former. An analysis of the position of the stepped methyl end-plane in the various subgroups of TAGs confirms most but not all suppositions found in the literature.

Keywords: triacylglycerols; powder diffraction; polymorph.


	Structure factor file (CIF format) (23.7 kbytes) [ doi:10.1107/S0108768108004813/dr5018SES-B2-SC1638-250K-Esup3.hkl ] Contains datablock SES-B2-SC1638-250K-refl

	Structure factor file (CIF format) (22.1 kbytes) [ doi:10.1107/S0108768108004813/dr5018PEP-B2-SC1638-B-EEEsup5.hkl ] Contains datablock PEP-B2-SC1638-B-EEE-refl

	Structure factor file (CIF format) (151.8 kbytes) [ doi:10.1107/S0108768108004813/dr5018PSP-BETA2-R3-TRANSsup7.hkl ] Contains datablock PSP-BETA2-R3-TRANS-refl

	Structure factor file (CIF format) (23.7 kbytes) [ doi:10.1107/S0108768108004813/dr5018SSE-B2-1_3-SC1638-CRsup9.hkl ] Contains datablock SSE-B2-1_3-SC1638-CR-refl

	Structure factor file (CIF format) (78.2 kbytes) [ doi:10.1107/S0108768108004813/dr5018PSS-B2-SC1638-1_3-INsup11.hkl ] Contains datablock PSS-B2-SC1638-1_3-IN-refl

	Structure factor file (CIF format) (45.0 kbytes) [ doi:10.1107/S0108768108004813/dr5018PPS-B2-BSTEELCSEAT-Esup13.hkl ] Contains datablock PPS-B2-BSTEELCSEAT-refl

	Structure factor file (CIF format) (67.3 kbytes) [ doi:10.1107/S0108768108004813/dr5018PPE-B2-1_3-CH1635-B3sup15.hkl ] Contains datablock PPE-B2-1_3-CH1635-B3

	Structure factor file (CIF format) (113.5 kbytes) [ doi:10.1107/S0108768108004813/dr5018PMM-B2-TRANS2sup17.hkl ] Contains datablock PMM-B2-TRANS2-refl

	Structure factor file (CIF format) (33.2 kbytes) [ doi:10.1107/S0108768108004813/dr5018LMM-B2-1_3R-CH1731-2sup19.hkl ] Contains datablock LMM-B2-1-3R-CH1731-2-refl

	Structure factor file (CIF format) (52.7 kbytes) [ doi:10.1107/S0108768108004813/dr5018LLM-B2-1_3sup21.hkl ] Contains datablock LLM-B2-1-3-refl

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