Identification and Quantification of Polymorphism in the Pharmaceutical Compound Diclofenac Acid by Terahertz Spectroscopy and Solid-State Density Functional Theory

King, Matthew D.; Buchanan, William; Korter, Timothy M.

doi:10.1021/ac2001934

Cited by 109 publications

(111 citation statements)

References 36 publications

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“…In this study, the THz spectra of two diclofenac acid polymorphs were obtained by THz spectroscopy, and the vibrational characters of the observed absorptions were analyzed using solid-state Density Functional Theory (DFT). The results demonstrate the quantitative capacity of THz spectroscopy and the reliability and utility of solidstate DFT in the calculation of low-frequency vibrational motions [11].…”

Section: Introductionmentioning

confidence: 67%

Study of Antiviral Diclofenac by Surface-Enhanced Raman Spectroscopy

Ros¹

2017

J Pharma Care Health Sys

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Diclofenac is a medication that presents in its structure two benzene rings joined by an amine group presenting: The first ring two chlorine atoms, both in the ortho position with respect to the amino group and the second ring is bound to ethanoic acid, also in ortho position with respect to this amino group, thus showing the carboxylate group (COO-).We have studied the Raman spectrum of solid Diclofenac (DCF), their spectra in solution in methanol at different concentrations and Surface-Enhanced Raman Spectroscopy (SERS) with additives that increase the profile of spectra. The interaction of this molecule with Ag (that is in the colloid used in SERS), is significant on the two rings, the COO-and amine group and Cl atom and C 7 H 2 group, everyone in the structure of DCF.

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Section: Introductionmentioning

confidence: 67%

Study of Antiviral Diclofenac by Surface-Enhanced Raman Spectroscopy

Ros¹

2017

J Pharma Care Health Sys

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“…A steep background often appears in THz absorption spectra, which increases along with the frequency, and it cannot be reproduced from quantum calculations. For direct comparison between the calculated and experimental spectra, a simple simulated background signal was modeled and added to the calculated results, following the literature [28,29]. The THz spectrum was calculated by convolution with a Lorentzian line shape to reproduce the line shape of the observed spectrum at room temperature.…”

Section: Theoretical Density Functional Theory Calculationsmentioning

confidence: 99%

Detection of Methomyl, a Carbamate Insecticide, in Food Matrices Using Terahertz Time-Domain Spectroscopy

Baek

Kang

Hwang

et al. 2015

J Infrared Milli Terahz Waves

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The aim of this study was to investigate the feasibility of detecting methomyl, a carbamate insecticide, in food matrices (wheat and rice flours) using terahertz time-domain spectroscopy (THz-TDS). In the frequency range 0.1-3 THz, the characteristic THz absorption peaks of methomyl at room temperature were detected at 1 (33.4 cm −1 ), 1.64 (54.7 cm −1 ), and 1.89 (63.0 cm −1 ) THz. For detailed spectral analysis, the vibrational frequency and intensity of methomyl were calculated using solid-state density functional theory to mimic molecular interactions in the solid state. Qualitatively, the simulated spectrum was in good agreement with the experimental spectrum. Analysis of the individual absorption modes revealed that all of the features in the THz spectrum of methomyl were mainly generated from intermolecular vibrations. The peak appearing at 1 THz (33.4 cm −1 ) was then selected and tested for its suitability as a fingerprint for detecting methomyl in food matrices. Its absorbance was dose-dependently distinguishable from that of wheat and rice flours. The calibration curve of methomyl had a regression coefficient of >0.974 and a detection limit of <3.74 %. Accuracy and precision expressed as recovery and relative standard deviation in interday repeatability were in the ranges 78.0-96.5 and 2.83-4.98 %, respectively. Our results suggest that THz-TDS can be used for the rapid detection of methomyl in foods, but its sensitivity needs to be improved.

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“…However, modeling small molecules like amino acids is a good start towards revealing complex motions of large molecules. Many studies [9,10,11,12,13,12,14,15,16,17,18,19] based on DFT method have been devoted to understand the low-frequency vibrations of small molecules in solid state.…”

Section: Introductionmentioning

confidence: 99%

The effect of the flexibility of hydrogen bonding network on low-frequency motions of amino acids. Evidence from Terahertz spectroscopy and DFT calculations

Lukács

Bordács

et al. 2018

Spectrochimica Acta Part A: Molecular and Biomolecular Spectros

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Low-frequency modes of l-Asp and l-Asn were studied in the range from 0.1 to 3.0 THz using time-domain Terahertz spectroscopy and density functional theory calculation. The results show that PBE-D2 shows more success than BLYP-D2 in prediction of THz absorption spectra. To compare their low-frequency modes, we adopted "vibrational character ID strips" proposed by Schmuttenmaer and coworkers [Journal of Physical Chemistry B, 117, 10444(2013)]. We found that the most intense THz absorption peaks of two compounds both involve severe distortion of their hydrogen bonding networks. Due to less rigid hydrogen bonding network in l-Asp, the side chain (carboxyl group) of l-Asp exhibits larger motions than that (carboxamide group) of l-Asn in low-frequency modes.

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Identification and Quantification of Polymorphism in the Pharmaceutical Compound Diclofenac Acid by Terahertz Spectroscopy and Solid-State Density Functional Theory

Cited by 109 publications

References 36 publications

Study of Antiviral Diclofenac by Surface-Enhanced Raman Spectroscopy

Study of Antiviral Diclofenac by Surface-Enhanced Raman Spectroscopy

Detection of Methomyl, a Carbamate Insecticide, in Food Matrices Using Terahertz Time-Domain Spectroscopy

The effect of the flexibility of hydrogen bonding network on low-frequency motions of amino acids. Evidence from Terahertz spectroscopy and DFT calculations

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