Spectrophotometric determination of acidity constants of 4-(2′–thiazolylazo)- resorcinol (TAR) in water–organic mixtures

Benvidi, Ali; Heidari, Fatemeh; Mazloum-Ardakani, Mohammad; Hajishabani, Ali Mohammad; Ghasemi, Jahan B.

doi:10.1016/j.cclet.2010.01.015

Cited by 5 publications

(4 citation statements)

References 15 publications

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“…As a result, longer wavelengths were observed in 40 percent ethanol in water. 14 The described red shifts of the different species of caffeic acid obtained using the ab initio quantum mechanical method are in good agreement with the results of UV-Vis spectroscopy. The ab initio calculated Gibbs energy change shows red shifts of different species of caffeic acid.…”

Section: Resultssupporting

confidence: 77%

“…Solvent mixtures facilitate the determination of K a . [12][13][14][15] Mixtures of two or more solvents are used to achieve appropriate solvent properties. Mixtures of water and organic solvents are most frequently used.…”

Section: Introductionmentioning

confidence: 99%

“…Net analyte methods, as the part of the spectrum of a mixture that is unique for the analyte of interest, is orthogonal to the spectra of the interferences. Following a previous work for the determination of the acidity constant of TAR (4-(2′-hiazolylazo)resorcinol) in water-organic solvent binary mixtures by spectrophotometry using the Data Analysis (DATAN) program, 14 the acidity constant of TAR was determined by wavelet neural network (WNN). 10 The DATAN program, proposed by Momeni--Isfahani and Niazi, 23 calculates spectral profiles, concentrations and equilibrium constants.…”

Section: Introductionmentioning

confidence: 99%

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Determination of the pKa for caffeic acid in mixed solvent using the net analyte signal method and ab initio theory

Dadras

Benvidi

Namazian

et al. 2019

JSCS

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Due to the biological effects of phenolic acid components, polyphenol-rich foods are a significant part of human and animal diets. In this study, the acidity constants of caffeic acid (3,4-dihydroxycinnamic acid) in binary mixtures of ethanol-water were determined spectrophotometrically using the introduced net analyte signal (NAS) algorithm and an ab initio quantum mechanical method. The NAS is an efficient chemometric algorithm for analysis of acid-base equilibrium systems by a spectrophotometric method. At different pH values, the distribution of acid species is obtained from an absorption data matrix and this procedure enabled the pK a of caffeic acid to be obtained alternatively. The results showed that pK a1 (4.

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Section: Resultssupporting

confidence: 77%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Determination of the pKa for caffeic acid in mixed solvent using the net analyte signal method and ab initio theory

Dadras

Benvidi

Namazian

et al. 2019

JSCS

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“…One of the great limitations of the proposed method is the strong overlapping of chemical components involved in the equilibrium . Nowadays, with the development of mathematical methods in chemistry, this limitation can be easily solved using different chemometric methods . In the present study, because of the high spectral overlap of coumaric acid isomers, the two‐rank annihilation factor analysis (TRAFA) method was performed on the obtained spectrophotometric data.…”

Section: Introductionmentioning

confidence: 99%

Experimental and computational study of the pK_a of coumaric acid derivatives

Benvidi

Dadras

Abbasi

et al. 2019

J Chinese Chemical Soc

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The dissociation constant (pK a ) of a drug is a key parameter in drug discovery and pharmaceutical formulation. The hydroxy substituent has a significant effect on the acidity of hydroxycinnamic acid. In this work, the acidic constants of coumaric acids are obtained experimentally by spectrophotometry using the chemometric method and calculated theoretically using ab initio quantum mechanical method at the HF/6-31G* level of theory in combination with the SMD continuum solvation method. Rank annihilation factor analysis (RAFA) is an efficient chemometric technique based on the elimination of the contribution of one of the chemical components from the data matrix. RAFA cannot be performed because the pure spectrum of HA − is not available. So, two-rank annihilation factor analysis (TRAFA) is proposed for the determination of the pK a OF H 2 A. A comparison between the pK a values obtained previously by TRAFA for the molecules o-coumaric acid (4. 13, 9.58), m-coumaric acid (4.48, 10.35), and p-coumaric acid (4.65, 9.92) makes it clear that there is good agreement between the results obtained by TRAFA and ab initio quantum mechanical method.

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Application of principal component–wavelet neural network in spectrophotometric determination of acidity constants of 4-(2-thiazolylazo)-resorcinol

Benvidi

Heidari

Tabaraki

et al. 2011

Spectrochimica Acta Part A: Molecular and Biomolecular Spectros

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Spectrophotometric determination of acidity constants of 4-(2′–thiazolylazo)- resorcinol (TAR) in water–organic mixtures

Cited by 5 publications

References 15 publications

Determination of the pKa for caffeic acid in mixed solvent using the net analyte signal method and ab initio theory

Determination of the pKa for caffeic acid in mixed solvent using the net analyte signal method and ab initio theory

Experimental and computational study of the pK_a of coumaric acid derivatives

Application of principal component–wavelet neural network in spectrophotometric determination of acidity constants of 4-(2-thiazolylazo)-resorcinol

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Spectrophotometric determination of acidity constants of 4-(2′–thiazolylazo)- resorcinol (TAR) in water–organic mixtures

Cited by 5 publications

References 15 publications

Determination of the pKa for caffeic acid in mixed solvent using the net analyte signal method and ab initio theory

Determination of the pKa for caffeic acid in mixed solvent using the net analyte signal method and ab initio theory

Experimental and computational study of the pKa of coumaric acid derivatives

Application of principal component–wavelet neural network in spectrophotometric determination of acidity constants of 4-(2-thiazolylazo)-resorcinol

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Experimental and computational study of the pK_a of coumaric acid derivatives