scholarly journals Vibrational spectroscopic studies of hydrogen‒bonded complexes between 2,5-dihydroxy-P-benzoquinone and amines

2001 ◽  
Vol 15 (1) ◽  
pp. 33-44 ◽  
Author(s):  
MoustafaM. Habeeb ◽  
Hoda A. Al-Wakil ◽  
Aly El-Dissouky ◽  
Nesrine M. Refat
Keyword(s):  
Ir Spectra ◽  
Critical Behavior ◽  
Spectroscopic Studies ◽  
Base Line ◽  
Ir Absorption ◽  
Deep Minimum ◽  
Nitrogen Bases ◽  
Ft Ir ◽  
Bonded Complexes ◽  
Hydrogen Bonded

A series of 1 :1 hydrogen-bonded complexes between 2,5-dihydroxy-P-benzoquinone (DHBQ) and various nitrogen bases of different strengths were prepared. The FT-IR spectra of the prepared complexes were examined in different regions. It has been found that the protonic and carbonyl vibrations are strongly affected by protonation. The intensity of protonic vibrations was estimated, the base line was corrected by using Perkin-Elmer Paragon 1000 program. A maximum was found at pKa= 5.6 in the correlation between the intensity and pKa(amines) suggesting a critical behavior. The same value was located as a deep minimum in the correlation between the center of gravity of the protonic vibrations, vcgcm−1, and the pKaof the amines confirming the critical behavior in some of the studied complexes. The effect of the contribution of the second OH group to the IR absorption profile was discussed. Finally, the FT-IR spectra of some deuterated complexes were presented and analysed.

scholarly journals FTIR spectroscopic studies and AM1 semi‒empirical calculations of some hydrogen‒bonded complexes of 2,5‒dihydroxy‒3,6‒dichlorobenzoquinone and anilines

2003 ◽  
Vol 17 (1) ◽  
pp. 65-75 ◽  
Author(s):  
Moustafa M. Habeeb ◽  
Gamal A. Gohar
Keyword(s):  
Spectroscopic Studies ◽  
Empirical Method ◽  
Intersection Point ◽  
Proton Affinities ◽  
Substituted Anilines ◽  
Deep Minimum ◽  
Chloranilic Acid ◽  
Semi Empirical ◽  
Bonded Complexes ◽  
Hydrogen Bonded

Fourier transform infrared (FTIR) spectra of a series of 1 : 1 hydrogen-bonded complexes between 2,5-dihydroxy-3,6-dichlorobenzoquinone (chloranilic acid, CA) and anilines in the crystalline form were investigated. The correlation between the center of gravity of the protonic vibration bands (νcg, cm–1) and the calculated proton affinities of the investigated anilines (PA, kcal/mol) as well as the Hammett substituent constants, (σH) were presented. A deep minimum was located at PA = 210−211 kcal/mol and σH= 0.1 suggesting the existence of a critical behavior. The semi‒empiricalsemi‒empirical quantum mechanical method, AM1 was utilized to correlate the experimental FTIR data. The obtained data showed a reasonable consistency with the experimental results. An intersection point was recorded at PA = 210–211 kcal/mol in the correlations between the oxygen and nitrogen atomic charges, (q0and qN, esu), the OH and NH bond distances (ROHandRNH, Å) and PA values of the substituted anilines. The strict correlation between the experimental and the calculated results confirmed the validity of the AM1 semi-empirical method for studying chloranilic acid – anilines hydrogen-bonded complexes.

Infrared spectroscopic studies of hydrogen-bonded complexes in cryogenic sulutions

1987 ◽  
Vol 112 (3) ◽  
pp. 379-386 ◽  
Author(s):  
T.A. Iskanderov ◽  
Ya.M. Kimel'fel'd ◽  
E.M. Smirnova
Keyword(s):  
Spectroscopic Studies ◽  
Infrared Spectroscopic ◽  
Bonded Complexes ◽  
Hydrogen Bonded

Dynamic FT-IR Spectroscopic Studies of Silk Fibroin Films

1997 ◽  
Vol 51 (4) ◽  
pp. 545-547 ◽  
Author(s):  
Masashi Sonoyama ◽  
Mitsuhiro Miyazawa ◽  
Gen Katagiri ◽  
Hideyuki Ishida
Keyword(s):  
Ir Spectra ◽  
Phase Analysis ◽  
Silk Fibroin ◽  
Spectroscopic Studies ◽  
Cast Films ◽  
Dynamic Spectra ◽  
Ft Ir ◽  
Ir Spectroscopic ◽  
Overlapping Bands ◽  
Good Agreement

Dynamic FT-IR spectra in the amide I region were measured for silk fibroin cast films. Phase analyses of the dynamic spectra were carried out in order to separate them into several components which are due to the secondary structures of fibroin. These observations showed that peak positions of the amide I bands were in good agreement with those obtained by Fourier self-deconvolution procedures. In conclusion, phase analysis of dynamic FT-IR spectra is a powerful technique for separation of highly overlapping bands.

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