The crystal structure of calcium ascorbate dihydrate

Investigation ofL(+)-Ascorbic acid with Raman spectroscopy in visible and UV light

“…The crystal structures of several salts of AH 2 have been obtained, including the sodium salt NaAH (10), as well as calcium (27)(28)(29), strontium (30), lithium (31), thallium (32), and other ascorbates (33). The crystal structures were often found to contain various amounts of hydrate water in addition to one or more ascorbate ions that look much like the AH 2 depicted in Figure 1, although without H3.…”

“…The crystal structures were often found to contain various amounts of hydrate water in addition to one or more ascorbate ions that look much like the AH 2 depicted in Figure 1, although without H3. Interestingly, in, for example, the calcium dihydrate and thallium salts, two different ascorbate ions are present in the unit cell and-as in AH 2 -these ions assume quite different conformations (different torsion angles χ 1 and χ 3 around C2 O2 and C4 C5 bonds) (27)(28)(29)32). In addition, we note that the hydrogen-bonding tendencies of O2 and O3 in certain ascorbate salts seem to favor the formation of anion dimers in solution (1,12,28,(34)(35)(36)(37).…”

“….. Ho6 O6 interaction and some additional stabilization from its Ho5 placed centrally above the resonance ring system, at a distance of 2.38 Å from C3. When trying to understand the behavior of ascorbate salts in solution it is worth remembering that the O2 and O3 charges seem to favor the formation of anion dimers via hydrogen bonding, and this tendency tends to complicate things further, as discussed in the literature (1,12,28,(34)(35)(36)(37). These features have not been studied here.…”

Schiff-base complexes of calcium: crystal structure analysis of dinitrato[N,N'-propane-1,3-diylbis(salicylideneimine)]calcium(II) and the spectroscopic properties of some related complexes

“…In Ca 2-(NO3)4(OH2) s (Ribfir et al, 1973) the five bond lengths to nitrate O atoms vary between 2.477 and 2-853 A whilst those to water are between 2.414 and 2.475 A. In diaquabis(L-ascorbato)calcium(II) (Hvoslef & Kjellevold, 1974) eight O atoms form a distorted square antiprism about Ca, and the bond lengths fall in the range 2.409-2.520 A.…”

Comparison of two independent determinations of the structure of calcium L-ascorbate dihydrate

“…Two simultaneous and independent determinations of the structure of calcium ascorbate dihydrate [Hearn & Bugg (1974), Hvoslef & Kjellevold (1974), hereafter HB and HK respectively] were published without detailed comparison. The monoclinic unit-cell orientations chosen by HK and HB differ, making casual comparison harder than usual and emphasizing the need for more formal treatment, such as is made in the present communciation.…”