Vibrational analysis of neat liquid tert-butylmethylether

Beć, Krzysztof B.; Kwiatek, Anna; Hawranek, J.P.

doi:10.1016/j.molliq.2014.02.028

Cited by 15 publications

(7 citation statements)

References 20 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In contrast, for IR and Raman spectroscopy, this limitation is less severe due to its more simple spectra with milder fundamental band overlapping [27,28]. Coincidently, quantum chemistry offers affordable methods (harmonic approximation) for the adequately accurate simulation of IR and Raman spectra [29,30]. In contrast, prediction of NIR bands require resource intensive anharmonic methods [31,32].…”

Section: Introductionmentioning

confidence: 99%

Distinct Difference in Sensitivity of NIR vs. IR Bands of Melamine to Inter-Molecular Interactions with Impact on Analytical Spectroscopy Explained by Anharmonic Quantum Mechanical Study

et al. 2019

View full text Add to dashboard Cite

Melamine (IUPAC: 1,3,5-Triazine-2,4,6-triamine) attracts high attention in analytical vibrational spectroscopy due to its misuse as a food adulterant. Vibrational spectroscopy [infrared (IR) and Raman and near-infrared (NIR) spectroscopy] is a major quality control tool in the detection and quantification of melamine content. The physical background for the measured spectra is not interpreted in analytical spectroscopy using chemometrics. In contrast, quantum mechanical calculations are capable of providing deep and independent insights therein. So far, the NIR region of crystalline melamine has not been studied by quantum mechanical calculations, while the investigations of its IR spectra have remained limited. In the present work, we employed fully anharmonic calculation of the NIR spectrum of melamine based on finite models, and also performed IR spectral simulation by using an infinite crystal model—periodic in three dimensions. This yielded detailed and unambiguous NIR band assignments and revised the previously known IR band assignments. We found that the out-of-plane fundamental transitions, which are essential in the IR region, are markedly more sensitive to out-of-plane inter-molecular interactions of melamine than NIR transitions. Proper description of the chemical surrounding of the molecule of melamine is more important than the anharmonicity of its vibrations. In contrast, the NIR bands mostly arise from in-plane vibrations, and remain surprisingly insensitive to the chemical environment. These findings explain previous observations that were reported in IR and NIR analytical studies of melamine.

show abstract

Section: Introductionmentioning

confidence: 99%

Distinct Difference in Sensitivity of NIR vs. IR Bands of Melamine to Inter-Molecular Interactions with Impact on Analytical Spectroscopy Explained by Anharmonic Quantum Mechanical Study

et al. 2019

View full text Add to dashboard Cite

show abstract

“…The former way may provide highly speculative assignments, while the latter method has limitations that prevent their common use in NIR spectroscopy. From the point of view of applied spectroscopy, there exists an essential difference in the applicability of quantum mechanical calculation of mid-infrared (MIR) [7,8,9] and NIR spectra. A simplistic and computationally inexpensive harmonic approximation fails to predict the overtones and combination modes [10].…”

Section: Introductionmentioning

confidence: 99%

Spectra–Structure Correlations in Isotopomers of Ethanol (CX3CX2OX; X = H, D): Combined Near-Infrared and Anharmonic Computational Study

et al. 2019

View full text Add to dashboard Cite

The effect of isotopic substitution on near-infrared (NIR) spectra has not been studied in detail. With an exception of few major bands, it is difficult to follow the spectral changes due to complexity of NIR spectra. Recent progress in anharmonic quantum mechanical calculations allows for accurate reconstruction of NIR spectra. Taking this opportunity, we carried out a systematic study of NIR spectra of six isotopomers of ethanol (CX3CX2OX; X = H, D). Besides, we calculated the theoretical spectra of two other isotopomers (CH3CD2OD and CD3CH2OD) for which the experimental spectra are not available. The anharmonic calculations were based on generalized vibrational second-order perturbation theory (GVPT2) at DFT and MP2 levels with several basis sets. We compared the accuracy and efficiency of various computational methods. It appears that the best results were obtained with B2PLYP-GD3BJ/def2-TZVP//CPCM approach. Our simulations included the first and second overtones, as well as binary and ternary combinations bands. This way, we reliably reproduced even minor bands in the spectra of diluted samples (0.1 M in CCl4). On this basis, the effect of isotopic substitution on NIR spectra of ethanol was accurately reproduced and comprehensively explained.

show abstract

“…The N07D basis set offers significant advantages in regard to both, as shown by Beć et al. 15,16 As the reference experimental NIR spectrum of RA was measured for amorphous solid state sample, Kirchler et al. 6 obviously did not applied any solvent model in their study.…”

Section: Application Of Anharmonic Methods For the Molecule Of Ramentioning

confidence: 99%

Quantum chemical calculation of NIR spectra of practical materials

Huck¹,

Beć

Grabska

et al. 2017

NIR news

View full text Add to dashboard Cite

In the third issue of the series on modern quantum chemical methods in the support role of NIR spectroscopy we continue to introduce the researchers from the field of experimental spectroscopy to practical aspects and applications of modern anharmonic theoretical approaches. The first two issues focused on explaining the necessary theoretical and practical background, allowing readers to get more familiar with the topic. An overview of recent literature reports highlighted the advantages stemming from using quantum chemical calculation in the support role to NIR spectroscopy. These deliberations were based on several cases of small-to medium-sized molecules. This part overviews the topic of applications of quantum theoretical methods to complex molecules with practical significance, which typically prove to be challenging objects for theoretical studies. An exemplary application of presented methodology to the case of Rosmarini folium biological samples is also examined here. The rosemary specific active compound, rosmarinic acid, is a relatively complex polyphenol with growing phytopharmaceutical importance, and therefore provides an excellent object of applied studies. The possibilities of combining the information stemming from quantum chemical calculation with the methods of advanced spectral data analysis, which are commonly used in experimental NIR spectroscopy (chemometrics, twodimensional (2D) correlation spectra) are also overviewed. Again, these deliberations are based directly on the most recent reports published in the field.

show abstract

Vibrational analysis of neat liquid tert-butylmethylether

Cited by 15 publications

References 20 publications

Distinct Difference in Sensitivity of NIR vs. IR Bands of Melamine to Inter-Molecular Interactions with Impact on Analytical Spectroscopy Explained by Anharmonic Quantum Mechanical Study

Distinct Difference in Sensitivity of NIR vs. IR Bands of Melamine to Inter-Molecular Interactions with Impact on Analytical Spectroscopy Explained by Anharmonic Quantum Mechanical Study

Spectra–Structure Correlations in Isotopomers of Ethanol (CX3CX2OX; X = H, D): Combined Near-Infrared and Anharmonic Computational Study

Quantum chemical calculation of NIR spectra of practical materials

Contact Info

Product

Resources

About