Untitled

Toscani, Siro; Dzyabchenko, A. V.; Агафонов, В.; Dugué, Jérôme; Céolin, R.

doi:10.1023/a:1016058123659

Cited by 23 publications

(16 citation statements)

References 4 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…At temperature about 400 K, β-polymorph is transformed to γ-polymorph. While the α−to γtransition temperature obtained from 14 N NQR, is the same as the one obtained by the DSC measurement [38,42], the βto γtransition temperature obtained from 14 N NQR measurements is about 10 K higher. From Figures 3 and 6 it is additionally evident that α-polymorph is not abundantly directly transformed to γ-polymorph, but preferably via the formation of intermediate β-polymorph that then transforms into γ-polymorph.…”

Section: N Nqr In Sulfanilamidesupporting

confidence: 71%

Nuclear Quadrupole Resonance (NQR)—A Useful Spectroscopic Tool in Pharmacy for the Study of Polymorphism

et al. 2020

View full text Add to dashboard Cite

Nuclear Quadrupole Resonance (NQR) spectroscopy has been known for 70 years. It is suitable for the study of measured (poly)crystalline chemical compounds containing quadrupole nuclei (nuclei with spin I ≥ 1) where the characteristic NQR frequencies represent the fingerprints of these compounds. In several cases, 14N NQR can distinguish between the polymorphic crystalline phases of active pharmaceutical ingredients (APIs). In order to further stimulate 14N NQR studies, we review here several results of API polymorphism studies obtained in Ljubljana laboratories: (a) In sulfanilamide, a clear distinction between three known polymorphs (α, β, γ) was demonstrated. (b) In famotidine, the full spectra of all seven different nitrogen positions were measured; two polymorphs were distinguished. (c) In piroxicam, the 14N NQR data helped in confirming the new polymorphic form V. (d) The compaction pressure in the tablet production of paracetamol, which is connected with linewidth change, can be used to distinguish between producers of paracetamol. We established that paracetamol in the tablets of six different manufacturers can be identified by 14N NQR linewidth. (e) Finally, in order to get an extremely sensitive 14N NQR spectrometer, the optical detection of the 14N NQR signal is mentioned.

show abstract

Section: N Nqr In Sulfanilamidesupporting

confidence: 71%

Nuclear Quadrupole Resonance (NQR)—A Useful Spectroscopic Tool in Pharmacy for the Study of Polymorphism

et al. 2020

View full text Add to dashboard Cite

show abstract

“…Sulfanilamide was found to crystallize in at least four different polymorphs: α, β, γ, and δ (see Figure S1, Supporting Information). − The occurrence of polymorphism in SA has been ascribed to the relevance of several types of intermolecular interactions in determining the crystal structures of the compound, in particular intermolecular hydrogen bonds of the N–H···OS type and dispersion interactions between aromatic rings. These interactions allow for establishment of different types of cross-linked three-dimensional networks, in a similar way as found, for example, for pyrazinamide …”

Section: Introductionmentioning

confidence: 99%

Conformational Landscape, Photochemistry, and Infrared Spectra of Sulfanilamide

2013

View full text Add to dashboard Cite

A combined matrix isolation FTIR and theoretical DFT(B3LYP)/6-311++G(3df,3pd) study of sulfanilamide (SA) was performed. The full conformational search on the potential energy surface of the compound allowed the identification of four different minima, all of them bearing the sulfamide nitrogen atom placed in the perpendicular orientation relatively to the aromatic ring and differing from each other in the orientation of the hydrogen atoms connected to the two nitrogen atoms of the molecule. All conformers were predicted to be significantly populated in the gas phase (at 100 °C, their relative populations were estimated as being 1:0.9:0.3:0.2). However, in agreement with the theoretically calculated low-energy barriers for conformational isomerization, in the low-temperature matrices, only the most stable conformer could be observed, with the remaining forms being converted into this form during matrix deposition (conformational cooling). The unimolecular photochemistry of matrix-isolated SA (in both argon and xenon) was also investigated. Upon broadband UV irradiation (λ > 215 nm), two photofragmentation pathways were observed: the prevalent pathway (A), leading to extrusion of sulfur dioxide and simultaneous formation of benzene-1,4-diamine, which then converts to 2,5-cyclohexadiene-1,4-diimine, and the minor pathway (B), conducting an γ-cleavage plus [1,3] H-atom migration from the sulfamide group to the aromatic ring, which leads to formation of iminosulfane dioxide and aniline, the latter undergoing subsequent phototransformation into cyclohexa-2,5-dien-1-imine. Finally, the crystalline polymorph of SA resulting from warming (265 K) the amorphous solid obtained from fast cooling of the vapor of the compound onto the cold (13 K) substrate of the cryostat was identified spectroscopically, and found to be the γ-crystalline phase, the one exhibiting in average longer H-bonds and an infrared spectrum resembling more that of the low temperature SA glass. Full assignment of the infrared spectra of this crystalline variety as well as of those of the β-polymorph room temperature crystalline sample and low temperature amorphous state was undertaken with help of theoretical results obtained for the crystallographically relevant dimer of SA.

show abstract

“…Therefore, the andˇforms must be enantiotropically related, but the situation in respect of˛/ˇand˛/ is not clear. Burger 13 and Toscani and co-workers 24,25 reported the˛anď forms as monotropically related, but this is partly based on small melting enthalpy differences on samples of doubtful polymorphic purity. Sekiguchi et al 14 suggested that they are enantiotropes with a transition point below room temperature.…”

Section: Introductionmentioning

confidence: 99%

Effects of polymorphic differences for sulfanilamide, as seen through ¹³C and ¹⁵N solid‐state NMR, together with shielding calculations

Portieri

Harris

Fletton

et al. 2004

Magnetic Reson in Chemistry

View full text Add to dashboard Cite

We recorded both carbon-13 and nitrogen-15 NMR spectra of the three solid forms of sulfanilamide most commonly known. This study led to an interpretation of the solid-state effects seen in cross-polarization magic angle spinning spectra. Relaxation times for the different forms were measured. These show different behaviour for the three forms, arising from mobility variations. To obtain information on local environments, static spectra and spinning sideband manifolds were recorded and analysed for the 15N resonances, using isotopically enriched samples. Shielding asymmetries and anisotropies for the two nitrogen nuclei were obtained, showing very different behaviour for the two sites. Shielding calculations were carried out for both 13C and 15N nuclei, and the results are discussed in relation to the experimental values.

show abstract

Untitled

Abstract: Provided enthalpy and volume changes at the transitions are accurate enough, it is possible to draw a p, T diagram that accounts for the stability hierarchy of polymorphs.

Cited by 23 publications

References 4 publications

Nuclear Quadrupole Resonance (NQR)—A Useful Spectroscopic Tool in Pharmacy for the Study of Polymorphism

Nuclear Quadrupole Resonance (NQR)—A Useful Spectroscopic Tool in Pharmacy for the Study of Polymorphism

Conformational Landscape, Photochemistry, and Infrared Spectra of Sulfanilamide

Effects of polymorphic differences for sulfanilamide, as seen through ¹³C and ¹⁵N solid‐state NMR, together with shielding calculations

Contact Info

Product

Resources

About

Untitled

Abstract: Provided enthalpy and volume changes at the transitions are accurate enough, it is possible to draw a p, T diagram that accounts for the stability hierarchy of polymorphs.

Cited by 23 publications

References 4 publications

Nuclear Quadrupole Resonance (NQR)—A Useful Spectroscopic Tool in Pharmacy for the Study of Polymorphism

Nuclear Quadrupole Resonance (NQR)—A Useful Spectroscopic Tool in Pharmacy for the Study of Polymorphism

Conformational Landscape, Photochemistry, and Infrared Spectra of Sulfanilamide

Effects of polymorphic differences for sulfanilamide, as seen through 13C and 15N solid‐state NMR, together with shielding calculations

Contact Info

Product

Resources

About

Effects of polymorphic differences for sulfanilamide, as seen through ¹³C and ¹⁵N solid‐state NMR, together with shielding calculations