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Solid state linear-dichroic infrared (IR-LD) spectroscopic characterization of α-and β-glycine polymorphs

100%
Ivanova B.
Open Chemistry
|
2006
|
vol. 4
|
issue 1
111-117
EN
IR-LD spectroscopic analysis using nematic liquid crystal suspension as a solid-state orientation technique and the reducing-difference procedure for polarized spectra interpretation are applied to the α-and β-polymorphs of glycine. Both structural analysis and detailed IR band assignments were carried out.
2
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Ab initio and infrared spectral study of 4′-substituted phenylthiolbenzoates

63%
Ivanova B., Arnaudov M.
|
EN
The geometry of the 4′-cyano-(4′-CNPTB) and the 4′-methoxy-(4′-MePTB) phenylthiolbenzoates were obtained by ab initio calculations employing 6–31G basis set at Hartee-Fock level of theory. The results predict an extended form of the molecules and torsional angle between the phenyl rings at 90.85(6)0 and 90.87(3)0, respectively. On the basis of vibrational analysis the frequency assignment was carried out. The calculated frequencies were compared with the experimental IR spectral data in carbon tetrachloride, carbon disulfide solutions and in solid state.
3
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Solid-state IR-LD spectroscopy of codeine and N-norcodeine derivatives

51%
Bakalska R., Ivanova B., Kolev T.
Open Chemistry
|
2006
|
vol. 4
|
issue 3
533-542
EN
Linear-dichroic infrared spectra (IR-LD) of 3-ethoxy-4-(N-norcodeino-)cyclobutene-1,2-dione (1) and codeine dihydrogenphosphate (Codeinum phosphoricum) (2), oriented as solid suspensions in nematic liquid crystals, have been measured. IR characteristic band assignments were made, and used in stereo-structural predictions. The results were compared with crystallographic structures of similar organic systems, and found to be in good agreement.
4
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A reducing-difference IR-spectral study of 4-aminopyridine

51%
Arnaudov M., Ivanova B., Dinkov S.
Open Chemistry
|
2004
|
vol. 2
|
issue 4
589-597
EN
The IR-spectra of 4-aminopyridine (4-AP) in solution and in the solid state have been analyzed, using the reducing-difference procedure. Defining a more precise band assignment of a part of the characteristic frequencies of 4-AP, the data obtained proved in particular a Fermi-resonance splitting of the symmetric NH2-stretch.
5
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IR-spectral study of photoinduced tautomerization in 1,3-diphenyl-pyrazol-5-one

51%
Ivanova B., Tchapkanov A., Arnaudov M., Petkov I.
Open Chemistry
|
2003
|
vol. 1
|
issue 4
356-365
EN
The UV-photoinduced prototropic isomerization of 1,3-diphenyl pyrazol-5-one (DPhP) embedded in polyvinyl chloride (PVC) film is studied by means of difference in IR spectral analysis. The initially existing CH-form in non-irradiated compound is transformed to NH-form, and a hydrochloride salt is stabilized because of the photodegradation of the PVC. An additional comparative IR spectral study of DPhP in different solutions as well as of its hydrochloride salts in solid state is also carried out.
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