Hydrogen-bonded complexes between mesogenic heterocyclic Schiff's bases and mesogenic 4- n -nonyloxybenzoic acid: mesomorphic behaviour, FTIR study and PM3 semi-empirical calculations

2003 ◽  
Vol 30 (3) ◽  
pp. 297-304 ◽  
Author(s):  
M. Parra ◽  
J. Alderete ◽  
C. Zunñiga ◽  
V. Jimenez ◽  
P. Hidalgo
Keyword(s):  
Schiff’S Bases ◽  
Ftir Study ◽  
Schiff's Bases ◽  
Heterocyclic Schiff's Bases ◽  
Semi Empirical ◽  
Bonded Complexes ◽  
Hydrogen Bonded

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.

scholarly journals Matrix isolation FTIR study of hydrogen-bonded complexes of methanol with heterocyclic organic compounds

RSC Advances ◽  
2017 ◽  
Vol 7 (5) ◽  
pp. 2503-2512 ◽  
Author(s):  
Xiaotong Jiang ◽  
Shijie Liu ◽  
Narcisse T. Tsona ◽  
Shanshan Tang ◽  
Lei Ding ◽  
...  
Keyword(s):  
Ftir Spectroscopy ◽  
Organic Compounds ◽  
Heterocyclic Compounds ◽  
Theoretical Calculations ◽  
Matrix Isolation ◽  
Ftir Study ◽  
Bonded Complexes ◽  
Hydrogen Bonded

Hydrogen bonded complexes of heterocyclic compounds with methanol were studied using matrix isolation FTIR spectroscopy and theoretical calculations.

scholarly journals Synthesis and Characterization of New Heterocyclic Schiff's Bases from Methyl 4-Hydroxybenzoate

2016 ◽  
Vol 19 (3) ◽  
pp. 28-33
Author(s):  
Saja S. Abbood ◽  
◽  
Jawad K. Shneine ◽  
Ahmed Ahmed ◽  
◽  
...  
Keyword(s):  
Synthesis And Characterization ◽  
Schiff’S Bases ◽  
Schiff's Bases ◽  
Heterocyclic Schiff's Bases

Green Synthesis, Characterization, DPPH and Ferrous Ion-chelating (FIC) Activity of Tetrakis-Schiff’s Bases of Terephthalaldehyde

2019 ◽  
Vol 16 (3) ◽  
pp. 249-255
Author(s):  
Momin Khan ◽  
Umar Ali ◽  
Anis Ur Rahman ◽  
Muhammad Ibrahim ◽  
Abdul Hameed ◽  
...  
Keyword(s):  
Antioxidant Activities ◽  
Radical Scavenging Activity ◽  
Radical Scavenging ◽  
Aromatic Aldehydes ◽  
Ferrous Ion ◽  
Future Research ◽  
Scavenging Activity ◽  
Schiff’S Bases ◽  
Schiff's Bases ◽  
Antioxidant Agents

Background: The role of small molecules as antioxidants to prevent the oxidation of other molecules and inhibit them from radical formation is the area of much interest to cure disease especially cancer. Moreover, the antioxidants play important role as stabilizers to prevent oxidation of fuels and lubricants. </P><P> Methods: In the present study, fifteen tetrakis-Schiff’s bases derivatives (1-15) were synthesized and screened for their antioxidant activities. Compounds 1-15 were synthesized by continuous stirring of reaction mixture of 1,4-bis (hydrazonomethyl)benzene (1 mmol) with various substituted aromatic aldehydes (2 mmol) in distilled water using acetic acid as catalyst at room temperature for 2-10 min. </P><P> Results: Our present study showed that all compounds are better ferrous ion-chelating agents except compound 1,4-bis((E)-((E)-(3,4-dimethoxybenzylidene)hydrazono)methyl)benzene (6) (IC50 = 329.26 &#177; 4.75 &#181;M) which has slightly low activity than the standard EDTA (IC50 = 318.40 &#177; 5.53 μM). In addition, DPPH radical scavenging activity of eleven compounds showed higher activity than the standard. However, remaining four compounds showed comparable radical scavenging activity to the standard DPPH (IC50 = 257.77 &#177; 4.60 &#181;M). </P><P> Conclusion: The series of fifteen Schiff’s bases (1-15) were synthesized and evaluated as antioxidants. From both assays, it has been demonstrated that most of the tetrakis-Schiff’s bases have potential to serve as leads for the development of antioxidant agents for future research.

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