Sucrose crystal structure

Rizzuto AB, Chen AC, Veiga ME Modification of the sucrose crystal structure to enhance pharmaceutical properties of excipient... 

The carbon backbone of the sucrose structure (Figure 3) is almost completely shielded by the o gen and hydrogen atoms and is expected to play only a minor role, if any, in solvent interactions. The relative contact areas of oj gens and hydrogens are orientation dependent and may impart a specific character to the different faces of the sucrose crystal. 

Cane sugar is generally available in one of two forms crystalline solid or aqueous solution, and occasionally in an amorphous or microcrystalline glassy form. Microcrystalline is here defined as crystals too small to show structure on x-ray diffraction. The melting point of sucrose (anhydrous) is usually stated as 186°C, although, because this property depends on the purity of the sucrose crystal, values up to 192°C have been reported. Sucrose crystallizes as an anhydrous, monodinic crystal, belonging to space group P21 (2). 

Figure 13.4 Torsional potential energy surfaces about the two C-O bonds linking the anomeric centers of sucrose at the MM3 level (a), 2-tetrahydrofuranyl-2-tetrahydropyranyl ether at the MM3 level (b), the same ether at the HF/6-31G(d) level (c), and the sum of the difference between the last two with the first (d). Thus, the last surface may be viewed either as the effect of the sucrose hydroxyl groups on the energy surface, evaluated at the MM3 level, added to the framework surface calculated at the ab initio level, or as an MM3 surface that has been partially conected quantum mechanically. Solid triangles represent anomeric torsions in sucrose units found in various X-ray crystal structures. Note that the hybrid surface is the only one that clusters the large majority of these triangles within low-energy contours...

The abnormal case is sucrose. Apparently the geometry of the molecule as observed in the crystal structure places constraints on the rotations which are not found in the sucrose moiety of the three trisaccharides. These constraints arise from the positions of the hydrogen atoms involved in the two intramolecular H-bonds, which are present in... 

The crystal structure of sucrose has been established by X-ray diffraction and neutron diffraction studies. The packing of sucrose molecules in the crystal lattice is determined mainly by hydrogen bond formation between hydroxyl groups of the fructose moiety. As an example of the type of packing of molecules in a sucrose crystal, a projection of the crystal structure along the a axis is shown in Figure 4-15. The dotted square represents one unit cell. The crystal faces indicated in this figure follow planes between adjacent sucrose molecules in such a way that the... 

Fig. 8.1. The four-center hydrogen bond in the crystal structure of sucrose by neutron diffraction (SUCROS04)...

Intramolecular hydrogen bonding in sucrose may be retained in aqueous solution. Empirical force field calculations suggest that the molecule of sucrose retains its crystal structure conformation in aqueous solution with the loss of one of the... 

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