Structure of mono-acid even-numbered β-triacylglycerols (original) (raw)
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Structure of C15-, C17- and C19-mono-acid β-triacylglycerols
Acta Crystallographica Section B Structural Science, 2001
The crystal structures of β-1,2,3-tris(pentadecanoyl)glycerol (β-C15C15C15), β-1,2,3-tris(heptadecanoyl)glycerol (β-C17C17C17) and β-1,2,3-tris(nonadecanoyl)glycerol (β-C19C19C19) have been determined from high-resolution X-ray powder diffraction data. Grid search and Rietveld refinement have been used to determine and refine the structures, respectively. As in β-1,2,3-tris(tridecanoyl)glycerol (β-C13C13C13) and the even-numbered mono-acid triacylglycerols, all three odd-numbered monoacid triacylglycerols crystallize in space group P\bar 1 with Z = 2 in an asymmetric tuning-fork conformation and have a lateral acyl chain packing resulting in a layered structure.
Structure of β-trimyristin and β-tristearin from high-resolution X-ray powder diffraction data
Acta Crystallographica Section B Structural Science, 2001
The crystal structures of β-1,2,3-tritetradecanoylglycerol (β-trimyristin or β-MMM) and β-1,2,3-trioctadecanoylglycerol (β-tristearin or β-SSS) have been determined from high-resolution synchrotron X-ray powder diffraction data. Grid search and Rietveld refinement have been used to determine and refine the structure, respectively. Both substances crystallize in space group P\\bar 1 with Z = 2. The unit-cell parameters for β-MMM are a = 12.0626 (6), b = 41.714 (1), c = 5.4588 (3) Å, α = 73.388 (4), β = 100.408 (5) and γ = 118.274 (4)°. For β-SSS the unit-cell parameters are a = 12.0053 (7), b = 51.902 (2), c = 5.4450 (3) Å, α = 73.752 (5), β = 100.256 (6) and γ = 117.691 (5)°. Soft-distance restraints have been applied to the molecules during refinement. For β-MMM the final Rp value obtained is 0.053 and for β-SSS the final Rp value is 0.041.
Structure of CnCn+2Cn-type (n = even) β′triacylglycerols
Acta Crystallographica Section B-structural Science, 2000
The crystal structures of the H 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 Iba2 and Z = 8. The unit-cell parameters of H -CLC are a = 57.368 , b = 22.783 (2) and c = 5.6945 (6) A Ê and the ®nal R value is 0.175. The unit-cell parameters of H -MPM are a = 76.21 (4), b = 22.63 (1) and c = 5.673
Acta Crystallographica Section B Structural Science, 2008
The β-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 β-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.
Recueil des Travaux Chimiques des Pays-Bas, 1976
Di-tert-butyl-2-nitrobenzoic acid (X) To 15.0 g of 3,s-di-tert-butylbenzoic acid (IX), dissolved in 100 ml concentrated sulfuric acid and cooled in an ice-salt bath, was added with stirring a mixture of20 ml of concentrated nitric acid (d = 1.5 I) , 150 mg sodium nitrite and 20 ml concentrated sulfuric acid in the course of 1.5 hours while the temperature was kept below 0". The mixture was stirred for 15 minutes below 00, after which the cooling bath was removed and stirring continued for another 15 minutes. The mixture was poured on ice and the precipitate collected by filtration, washed and dried; 17.9 g, m.p. 198-202". Recrystallisation from aqueous ethanol gave 16.8 g (94%) of pure X as fine white
Journal of Physics D: Applied Physics, 2015
The first simulation study of the crystallisation of a binary mixture of triglycerides using molecular dynamics simulations is reported. Coarse-grained models of tristearin (SSS) and tripalmitin (PPP) molecules have been considered. The models have been preliminarily tested in the crystallisation of pure SSS and PPP systems. Two different quenching procedures have been tested and their performances have been analysed. The structures obtained from the crystallisation procedures show a high orientation order and a high content of molecules in the tuning fork conformation, comparable with the crystalline α phase. The behaviour of melting temperatures for the α phase of the mixture SSS/PPP obtained from the simulations is in qualitative agreement with the behaviour that was experimentally determined.
Structure and polymorphism of 1,2-dioleoyl-3-acyl-sn-glycerols. Three- and six-layered structures
Biochemistry, 1985
Triacylglycerols, which usually contain at least one unsaturated fatty acid, are the most important forms of stored biological lipids in teleosts, mammals, and most plants. Since the physical properties of such mixed-chain triacylglycerols are poorly understood, a systematic study of such compounds has been initiated. Stereospecific 1,2-dioleoyl-3-acyl-sn-glycerols were synthesized with even carbon saturated fatty acyl chains of 14-24 carbons in length. Their polymorphic behavior was examined by differential scanning calorimetry and X-ray powder diffraction. The thermal behavior revealed from one to four major polymorphic transitions depending upon saturated chain length. Plots of enthalpy of fusion and entropy vs. carbon number for qelting of the most stable polymorph were linear throughout the series with slopes of 1 .O kcal/mol per carbon atom and 2.6 cal/(mol K) per carbbn atom, respectively. These slopes indicate that the saturated chains are packed in a well-ordered tightly packed lattice. When the compounds were rapidly cooled to 5 O C , X-ray powder diffraction revealed strong p' (ca. 3.8 and 4.2 A) reflections and weak /3 (ca. 4.6 A) reflections. The /3 subcell reflections intensified when the compounds were heated to within 5 O C of the meltihg temperature of the highest melting polymorph. Evidence of an 01 phase was not seen on 30-min X-ray exposures for any of the compounds. In the proposed packing arrangement the saturated and unsaturated chains are segregated into layers. The stable form of all compounds exhibits a triple layer packing mode in which a bilayer of oleoyl chains is segregated from an interdigitated layer of saturated chains. The thickness of the glycerol backbone normal to the base plane is about 4.1 A. The saturated chains are tilted 55.8' with.respect to the base plane. This tilt is close to the value of 56.5O obtained from the single crystal study of oleic acid, which may indicate that the saturated chains project from the glycerol backbone like a linear extension of the first nine carbons of the oleoyl chain. In addition, a metastable six-layer packing mode was identified for 1,2-dioleoyl-3-myristoyl-sn-glycerol. While some of the complex polymorphisms involve adjustments in chain packing, others may relate to transitions from unstable six-layer to stable three-layer structures.
Mixing Phase Behavior of Tripalmitin and Oleic-Rich Molecular Compound-Forming Triacylglycerols
Industrial & Engineering Chemistry Research, 2021
The binary phase behavior of triacylglycerol (TAG) mixtures constituted by PPP (tripalmitin) and either POP (1,3-dipalmitoyl-2-oleoyl-glycerol), OPO (1,3-dioleoyl-2-palmitoyl-glycerol), or MCPOP/OPO (molecular compound formed by POP/OPO at a 1:1 concentration ratio) was determined by differential scanning calorimetry (DSC), synchrotron (SR-) and laboratory-scale X-ray diffraction (XRD). Steric hindrance due to saturated-unsaturated acyl chain interactions and differences in the thermal stability of TAGs seemed to dictate the independent polymorphic crystallization and transformation observed under kinetic conditions, as well as the very asymmetric eutectic-type phase diagrams obtained from the study of thermodynamically stabilized PPP/POP, PPP/OPO, and PPP/MCPOP/OPO mixtures. Moreover, the solid integration determined for MCPOP/OPO in the βPPP crystalline phase (20-25%), halfway between that of OPO (<5%) and POP (30-35%), showed the ability of molecular compounds to tune the thermophysical properties of fat systems. This highlights the impact that molecular compoundforming TAGs may have on the efficient industrial separation of lipids, and suggest their potential applicability in the development of edible fat blends with tailored functionalities.
Alternation of Melting Points in Odd- and Even-Numbered Monoacid Triacylglycerols
Chemistry of Materials, 2001
Alternation of melting points in the series of odd-and even-numbered monoacid triacylglycerols has been known for a long time, but hitherto little experimental evidence has been available to support existing theories. In this paper the melting point alternation of-C n C n C n-type triacylglycerols is discussed, based on the crystal structures of-C n C n C n (n) number of C atoms per hydrocarbon chain) 10, 12, 14, 16, 18 and n) 13, described in this paper). The crystal structure of-1,2,3-tris(tridecanoyl)glycerol (-C 13 C 13 C 13) has been determined from high-resolution synchrotron X-ray powder diffraction data and is presented here. Grid search and Rietveld refinement have been used to determine and refine the structure, respectively. Like the even-numbered monoacid triacylglycerols,-C 13 C 13 C 13 is crystallized in an asymmetric tuning-fork conformation and its acyl chains are laterally packed, resulting in a layered structure. Within a molecular layer, the odd-and evennumbered monoacid triacylglycerols are identically packed, but the packing of adjacent molecular layers is different, clarifying the alternation of melting points. n C n-type (n) number of C atoms per hydrocarbon chain)
Characterization of the Nanoscale in Triacylglycerol Crystal Networks
Crystal Growth & Design, 2010
Here we report on the characterization of the nanoscale in triacylglycerol crystal networks of edible fats. Blends of tristearin and triolein were prepared in proportions between 20 and 100% w/w to achieve a wide range of supersaturations. Crystal networks were subjected to mechanical disruption using isobutanol at 10°C and visualized using cryogenic transmission electron microscopy (cryo-TEM). This method allowed the breakdown of spherulitic structures into their primary crystals: nanoplatelets of approximate sizes 150 Â 60 Â 30 nm to 370 Â 160 Â 40 nm depending on supersaturation conditions, and a length to width aspect ratio of 2.3. The method also allowed the visualization of bimolecular triacylglycerol lamellae within a cross-section of a nanoplatelet. The tristearin d-spacing (∼4.5 nm) and domain size (30-50 nm) of the (001) plane, by cryo-TEM and small-angle X-ray diffraction, agreed quantitatively. Scherrer analysis provided an accurate estimate of the cross-sectional thickness of the nanoplatelets and was linearly related to the length and width of the corresponding nanoplatelets, allowing in principle the use of small-angle X-ray diffraction as a rapid and accurate "nanocrystal sizer". A pictorial representation of the hierarchical structure of a triacylglycerol crystal network is presented. This work opens up the possibility of nanomanipulation of the structure of fats to target specific physical properties and physiological response.