The crystal structure of <scp>L</scp>-ascorbic acid, `vitamin C'. II. The neutron diffraction analysis

Hvoslef, J.

doi:10.1107/s0567740868004449

Cited by 81 publications

(44 citation statements)

References 3 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The influence of temperature on the chemical stability of L-ascorbic acid has mainly been studied in solution and thermal decomposition has rarely been studied in the solid state; only calorimetric and gravimetric data are available in the literature [4,5]. In addition, although the crystal structure of vitamin C is known for years [6], both from single-crystal X-ray and neutron diffraction measurements at and below room temperature [6][7][8][9][10][11][12][13], the influence of heating on crystalline Lascorbic acid has never been studied by X-ray diffraction.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Thermal expansion of L-ascorbic acid

Nicolaı̈

Tamarit

Céolin

et al. 2017

Eur. Phys. J. Spec. Top.

View full text Add to dashboard Cite

The specific volume of vitamin C has been investigated by X-ray powder diffraction as a function of temperature from 110 K up to complete degradation around 440K. Its thermal expansion is relatively small in comparison with other organic compounds with an expansivity  v of 1.2(3) ×10 -4 K -1 . The structure consists of strongly bound molecules in the ac plane through a dense network of hydrogen bonds. The thermal expansion is anisotropic. Along the b axis, the expansion has most leeway and is about 10 times larger than in the other directions.2

show abstract

Section: Introductionmentioning

confidence: 99%

“…The references of the most useful CSD files have been compiled in Table 1 together with a few other publications on the structure [6][7][8][9][10][11]. L-ascorbic acid crystallizes in the monoclinic system with the non-centrosymmetric space group P2 1 , with 4 molecules per unit-cell (Z = 4).…”

Section: Introductionmentioning

confidence: 99%

Thermal expansion of L-ascorbic acid

Nicolaı̈

Tamarit

Céolin

et al. 2017

Eur. Phys. J. Spec. Top.

View full text Add to dashboard Cite

show abstract

“…The special ~b-(six-)circle diffractometer described earlier (HiJmmer, Bondza & Weckert, 1987) The fractional atomic coordinates were taken from: (1) Kartha & De Vries (1961); (2) Brown & Sadanaga (1965); (3) Hvoslef (1968) [warning: in this paper a left-handed coordinate system is used]; (4) Berman (1970); (5) Lehmann & Nunes (1980); (6) Burzlaff (1988); (7) Paulus (1988); (8) Weckert (1990a); (9) Weckert (1990b); (10) Weckert (1990c).…”

Section: Methodsmentioning

confidence: 99%

Direct measurements of triplet phase relationships of organic non-centrosymmetric structures using synchrotron radiation

Hümmer¹,

Weckert²,

Bondza³

1990

Acta Cryst Sect A

View full text Add to dashboard Cite

Recent progress in experimental triplet phase determination by the method of three-beam diffraction for 0108-7673/90/050393-10503.00 non-centrosymmetric light-atom structures is reported. The measurements were carried out with a special 0-circle diffractometer installed at the DORIS II storage ring in Hamburg. Experimental results O 1990 International Union of Crystallography 394 DIRECT MEASUREMENTS OF TRIPLET PHASE RELATIONSHIPS confirm the theoretical considerations. In general, the ~-scan profiles consist of a phase-independent Umweganregung or AuJhellung part superimposed on a phase-dependent part due to the three-beam interference, which contains the phase information.Experimentally, Umweganregung and Aufhellung effects can be evaluated by comparison of the two centrosymmetrically related three-beam cases. It is shown that with moderate phase-independent effects the triplet phase can be determined with an accuracy of about 45 ° . IntroductionIn a recent paper (Hiimmer, Weckert & Bondza, 1989) we reported the direct measurements of triplet phases by means of three-beam interference experiments for two non-centrosymmetric test structures with relatively small unit cells using Cu radiation from a rotating-anode generator. It was shown that the threebeam interference effect leads to typical 0-scan profiles for triplet phases near 0, 180, +90 or -90 °.On the other hand, the theoretical considerations in the preceding paper (Weckert & Hiimmer, 1990) show that it should be possible to achieve a higher precision in experimental triplet phase determination in spite of phase-independent Umweganregung and Aufhellung effects superimposed on the interference effect. The three-beam interference between the primary diffracted wave and the Umweg wave gives rise to the typical 'ideal' 0-scan profiles which carry the phase information. It should be possible to evaluate the troublesome Umweganregung and Aufhellung effects by comparing the 0-scan profiles of two centrosymmetrically related three-beam cases 0/h/g and O/-h/-g which involve equal triples of structurefactor magnitudes but triplet phases of opposite sign if anomalous-dispersion effects can be neglected. However, because of the experimental systematic uncertainties the Umweganregung and Aufhellung should be avoided. Thus, the basic requirement for this procedure is that the primary, secondary and the coupling reflections have nearly equal intensities.Our method of quantitative determination of triplet phases is in some important aspects different from that proposed by Shen & Colella (1988) and Tang & Chang (1988).In the experiments of Shen & Collella the intensity change of very weak primary reflections caused by strong multiple reflections is used. The phase information is obtained from the asymmetry in the wings of the multiple-reflection peaks which are dominated by strong Umweganregung. The asymmetry decreases with decreasing cosine of the triplet phase. So the authors stated that only cos ~b can be determined.In the paper of Tang & Chang (1988) the ...

show abstract

“…[34] These include X-ray structures obtained at both ambient temperature (lascac10) [35] and at low temperatures: 120 K (lascac12) [36], 100 K (lascac14) and 90 K (lascac15) as well as a neutron diffraction refinement (lascac01) [37] of the hydrogen atom positions in the ambient temperature structure. In all cases the space group is P21, and there are four L-ascorbic acid molecules in the unit cell and two in the asymmetric unit, related to one another by a pseudo symmetry operation.…”

Section: Ascorbic Acid Crystal Structuresmentioning

confidence: 99%

“…Figure 4(a) shows an overlay of experimental (black contours) and simulated (grey contours) anisotropicisotropic correlation spectra of L-ascorbic acid. In this case the simulated spectrum was obtained by geometry optimization of the hydrogen positions only, starting from the neutron refinement (lascac01) [37].…”

Section: H Shift Parametersmentioning

confidence: 99%

1 H CSA parameters by ultrafast MAS NMR: Measurement and applications to structure refinement

Miah

Cresswell

Iuga

et al. 2017

Solid State Nuclear Magnetic Resonance

View full text Add to dashboard Cite

A 1 H anisotropic-isotropic chemical shift correlation experiment which employs symmetry-based recoupling sequences to reintroduce the chemical shift anisotropy in ν1 and ultrafast MAS to resolve 1 H sites in ν2 is described. This experiment is used to measure 1 H shift parameters for L-ascorbic acid, a compound with a relatively complex hydrogen-bonding network in the solid. The 1 H CSAs of hydrogen-bonded sites with resolved isotropic shifts can be extracted directly from the recoupled lineshapes. In combination with DFT calculations, hydrogen positions in crystal structures obtained from X-ray and neutron diffraction are refined by comparison with simulations of the full two-dimensional NMR spectrum. The improved resolution afforded by the second dimension allows even unresolved hydrogen-bonded sites 1 H to be assigned and their shift parameters to be obtained.

show abstract

The crystal structure of L-ascorbic acid, `vitamin C'. II. The neutron diffraction analysis

Cited by 81 publications

References 3 publications

Thermal expansion of L-ascorbic acid

Thermal expansion of L-ascorbic acid

Direct measurements of triplet phase relationships of organic non-centrosymmetric structures using synchrotron radiation

1 H CSA parameters by ultrafast MAS NMR: Measurement and applications to structure refinement

Contact Info

Product

Resources

About