scholarly journals A reducing-difference IR-spectral study of 4-aminopyridine

2004 ◽  
Vol 2 (4) ◽  
pp. 589-597 ◽  
Author(s):  
Michail Arnaudov ◽  
Bojidarka Ivanova ◽  
Shishman Dinkov
Keyword(s):  
Solid State ◽  
Ir Spectra ◽  
Spectral Study ◽  
Fermi Resonance ◽  
Characteristic Frequencies ◽  
Band Assignment

AbstractThe 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.

Circular dichroism and infrared study of β-turn formation in repeat peptides of elastin

1987 ◽  
Vol 52 (5) ◽  
pp. 1356-1361
Author(s):  
S. Abdel Rahman ◽  
M. Elsafty ◽  
A. Hattaba
Keyword(s):  
Circular Dichroism ◽  
Solid State ◽  
Ir Spectra ◽  
Chain Length ◽  
Room Temperature ◽  
Infrared Study ◽  
Feature Characteristic ◽  
C 50 ◽  
The Stability ◽  
Circular Dichroïsm

The conformation of elastin-like peptides Boc-Ala-Pro-Gly-Val-APEGM, Boc-Ala-Pro-Gly-Val-Gly-Val-APEGM, Boc-Ala-Pro-Gly-Val-Ala-Pro-Gly-Val-Gly-Val-APEGM, Boc-Ala-Pro-Gly-Val-Gly-Val-Ala-Pro-Gly-Val-Gly-Val-APEGM were examined in solution using circular dichroism at 30 °C, 50 °C, and 70 °C and in solid state by IR at room temperature. The studies show that the β-turn is a significant conformational feature for peptides under investigation in solution at 30 °C and 50 °C, but at 70 °C the tetra, hexa, and decapeptides show the CD feature characteristic of the β-structure while the dodecapeptide spectra show the presence of β-turn which indicates the stability of the β-turn at this chain length. The IR spectra show that in the solid state at room temperature all investigated peptides assume essentially a β-turn except the tetrapeptide which present evidence of antiparallel β-structure. The β-turn contribution in the IR spectra increases with the increase of the chain length of the peptide.

Evaluation of solid state of rice flours produced by different milling processes using ATR-FTIR spectroscopy

2021 ◽  
Author(s):  
Daitaro Ishikawa ◽  
Jiamin Yang ◽  
Chiaki Ichikawa ◽  
Tomoyuki Fujii
Keyword(s):  
Solid State ◽  
Ir Spectra ◽  
Ftir Spectroscopy ◽  
Water Activity ◽  
Rice Flour ◽  
Milling Process ◽  
Adsorption Properties ◽  
Water Molecules ◽  
Rice Flours ◽  
Changes Of State

ABSTRACT This study evaluated the influence of the milling process on solid state of rice flours according to water activity using ATR-FTIR. A band at 1740 cm−1 attributed to the C=O stretching of lipids was detected for crystalline samples, and it disappeared at a high aw range. The CH band at 2930 cm−1 of crystalline samples gradually shifted to a higher wavenumber with aw. This band of the α-formed and wet-milled samples shifted to higher wavenumbers above 0.8aw. A band due to OH stretching mode in the 3500-3000 cm−1 region did not shift with aw. The result obtained from IR spectra suggests that the parameter K calculated by Guggenheim–Anderson–de Boar model reflected not only the interaction between water molecules but also the changes of state in solids. Consequently, the results from this study provide insights about the adsorption properties of nonideal solids such as rice flour.

Prototropic Tautomerism and Some Features of the IR Spectra of 2-(3-Chromenyl)-1-hydroxyimidazoles

2019 ◽  
Vol 72 (9) ◽  
pp. 699 ◽  
Author(s):  
Polina A. Nikitina ◽  
Tatiana Yu. Koldaeva ◽  
Vitaly S. Mityanov ◽  
Vladimir S. Miroshnikov ◽  
Elizaveta I. Basanova ◽  
...  
Keyword(s):  
Solid State ◽  
Ir Spectra ◽  
Carbonyl Group ◽  
Tautomeric Form ◽  
Imidazole Ring ◽  
General Effect ◽  
Dmso Solution ◽  
Prototropic Tautomerism ◽  
Leading Role ◽  
Equilibrium Shift

Prototropic tautomerism of 2-(3-chromenyl)-1-hydroxyimidazoles with various substituents in the chromenyl moiety (1-hydroxyimidazole – imidazole N-oxide) was studied by means of 1H NMR and IR spectroscopies. It was demonstrated that in d6-DMSO solution, the substituents in the chromenyl ring have no influence on the equilibrium shift: the prevalence of the N-oxide tautomeric form is caused by the possibility of stabilization of the planar structure with the help of the carbonyl group in position 5 of the imidazole ring. In contrast, in the solid state the general effect of the chromenyl substituent in position 2 of imidazole plays the leading role. The increase in general electron-withdrawing effect of the chromenyl moiety leads to the prevalence of the imidazole N-oxide tautomer.

Solid-state Anomalies in IR Spectra of Compounds of Pharmaceutical Interest

1976 ◽  
Vol 65 (9) ◽  
pp. 1400-1403 ◽  
Author(s):  
S.C. Mutha ◽  
W.B. Ludemann
Keyword(s):  
Solid State ◽  
Ir Spectra

Gradual H/D substitution in synthetic germanium bearing talcs: a method for infrared band assignment

Clay Minerals ◽  
1999 ◽  
Vol 34 (2) ◽  
pp. 365-374 ◽  
Author(s):  
F. Martin ◽  
S. Petit ◽  
O. Grauby ◽  
M. P. Lavie
Keyword(s):  
Ir Spectra ◽  
Spectral Shift ◽  
Hydroxyl Groups ◽  
Ir Absorption ◽  
Infrared Band ◽  
Absorption Bands ◽  
Band Assignment ◽  
Ir Bands

AbstractThe deuteration technique was used to assign unknown infrared (IR) bands of Ge-bearing talcs. Procedures to achieve partial or complete H/D replacement in synthetic Ge-bearing (Mg, Ni and Co)-talcs have been investigated. From the spectral shift of IR absorption bands in the 4000–300 cm-1 region resulting from the H-D substitution, the IR bands of vibrations of Ge-bearing talcs could be identified and synthetic Ge-bearing talcs showed significantly different IR spectra from those for Si-talcs. After deuteration of synthetic Ge-bearing talcs, the unknown bands were attributed either to hydroxyl groups or to Ge–O vibrations of the clay skeleton, and the spectra were interpreted fully.

scholarly journals Compounds of Complex Halo and Pseudohalo Acids of the Group II B Metals, Part I Etherate, Pyridine and Aniline Compounds of Zn(II)

1979 ◽  
Vol 34 (8) ◽  
pp. 1101-1106 ◽  
Author(s):  
A. G. Galinos ◽  
J. K . Kouinis ◽  
P. V. Ioannou ◽  
Th. F . Zafiropoulos ◽  
S. P. Perlepes
Keyword(s):  
Solid State ◽  
Ir Spectra ◽  
Chemical Properties ◽  
Physical And Chemical Properties ◽  
Uv And Ir Spectra ◽  
Group Ii ◽  
Physical And Chemical ◽  
And Chemical Properties

The preparation of sixteen new etherate, pyridine and aniline compounds of complex halo and pseudohalo acids of Zn(II) is reported.The study of some physical and chemical properties as well as the UV and IR spectra of these compounds are discussed. Tetrahedral structures are proposed for all compounds in the solid state

Compounds of Complex Halo and Pseudohalo Acids of the Group II B Metals, Part HI [1]Spectral Studies of the Hgl-3 Ion

1980 ◽  
Vol 35 (10) ◽  
pp. 1244-1246 ◽  
Author(s):  
S. P. Perlepes ◽  
Th. F. Zafiropoulos ◽  
J. K. Kouinis ◽  
A. G. Galinos
Keyword(s):  
Solid State ◽  
Ir Spectra ◽  
Spectral Studies ◽  
Uv Spectrum ◽  
Anionic Species ◽  
Group Ii

Abstract A study has been made of the Far-IR spectra (250-30 cm-1) of the complexes HHgI3 · 2 Py and HHgI3 · 2 An (Py = pyridine and An = aniline), in the solid state. Associated anionic structures are present in the two complexes.The UV spectrum of the aniline complex, in three solvents, shows that the HgI3- ion is the predominant anionic species in solution.

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