On the Relevance of Considering the Intermolecular Interactions on the Prediction of the Vibrational Spectra of Isopropylamine

Amado, Ana M.; Fiuza, Sónia M.; Carvalho, Luís A. E. Batista de; Ribeiro‐Claro, Paulo J. A.

doi:10.1155/2013/682514

Cited by 8 publications

(5 citation statements)

References 50 publications

(84 reference statements)

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“…The mPW1PW91 functional was applied, combined with the widely used 6-31G(d) basis set, as well as with the more extensive 6-31+G(d,p) (comprising one additional polarization function on hydrogen atoms and diffusion functions on nonhydrogen atoms), to compare the resulting activation energies. The choice of mPW1PW91, a one-parameter hybrid functional, is supported by previous works , on the validation of this theory level as an appropriate method for this kind of studies. Additionally, the more recent wB97XD functional (which includes corrections for long-range interactions and dispersion effects) was tested, yielding slightly worse results…”

Section: Methodsmentioning

confidence: 89%

FTIR Spectroscopy and DFT Calculations to Probe the Kinetics of β-Carotene Thermal Degradation

et al. 2019

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The thermal degradation of β-carotene in air was investigated. The sample was heated at different temperatures (90, 100, 115, and 130 °C) for periods of up to 8 h to perform a complete kinetic study, the product analysis having been carried out via infrared spectroscopy in attenuated total reflectance mode coupled to density functional theory (DFT) calculations. The kinetics of this thermal degradation process was found to follow a first-order scheme, with rate coefficients varying from k 90 °C = (2.0 ± 0.3) × 10 −3 to k 130 °C = (11.0 ± 0.7) × 10 −3 min −1 , the experimental activation energy having been calculated as (52 ± 1) kJ mol −1 . This E a value is close to the DFT energies corresponding to a C 15−15′ or a C 13−14 cis−trans isomerization, followed by the formation of a carotene−oxygen diradical, which was characterized for the first time. Comparison between the experimental and calculated infrared data confirmed the C 15−15′ -cis rupture as the predominant reaction pathway and retinal as the major degradation product.

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Section: Methodsmentioning

confidence: 89%

FTIR Spectroscopy and DFT Calculations to Probe the Kinetics of β-Carotene Thermal Degradation

et al. 2019

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“…Previous reports on the theoretical prediction of the vibrational spectra of cisdiamminedichloro-platinum (II) (cisplatin) and cisdiamminedichloro-palladium (II) [25,28] showed that the mPW1PW/6-31G* theory level yielded a good balance between the computational demands and the accuracy achieved. This theory level has also been demonstrated to be adequate for the description of hydrogen bonds involving N-H groups [24]. Despite these prior findings, the efficiency of the mPW1PW/6-31G * level was once more evaluated, within this new context, by comparison with the results obtained using a higher theory level that combines a long-range corrected hybrid functional, ωB97XD, with a much larger basis set, 6-311++G(2d,2p).…”

Section: Computational Detailsmentioning

confidence: 99%

“…Characterization of both free ligands and metal complexes has been performed by vibrational spectroscopy (Raman, Fourier transform infrared (FTIR) and inelastic neutron scattering (INS)) coupled to quantum chemical calculations [24][25][26][27][28][29][30][31][32][33][34].…”

Section: Introductionmentioning

confidence: 99%

On the correction of calculated vibrational frequencies for the effects of the counterions — α,ω-diamine dihydrochlorides

et al. 2015

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The present work provides sets of correction factors to adjust the calculated vibrational frequencies of a series of α,ω-diamines hydrochloride salts to account for the intermolecular interactions with the counterion. The study was performed using different theory levels for predicting the vibrational data of isolated dicationic α,ω-diamines and their hydrochloride forms, with and without the explicit account of the interactions with the chloride counterions. Different sets of correction factors were determined for each theory level considering the four smallest elements for the α,ω-diamines series, while their transferability and reliability was evaluated considering the larger elements of the series. The theory level simplification was also evaluated and was found to neither compromise the vibrational frequencies estimates nor the magnitude and accuracy of the pre-defined scaling factors. This suggests that transferability of the correction factors is possible not only for different diamines but also between different levels of theory with the averaged group correction factor, ζ g (a) , being the best choice to account for the effects of the N-H · · · Cl interactions. The possibility of simplifying the theory level without compromising efficiency and accuracy is additionally of utmost importance. This computational approach can constitute a valuable tool in the future for studying the hydrochloride forms of larger and more complex diamine systems. Graphical Abstract A computational approach that may constitute a valuable tool for studying the hydrochloride forms of large and complex diamine systems. Correction factors to adjust the vibrational frequencies calculated for isolated dicationic primary diamines for the effects of the interactions with chloride counterions, without their explicit account in the calculations, are presented and evaluated for eficiency.

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“…In many cases, the simple match between predicted and observed IR spectra may suffice. However, the interpretation of the vibrational spectra in terms of the atomic motions related to each observed signal can also provide valuable information about the chemical systems, its structure and behavior . For example, the contribution of N–H stretching motion to the different high-frequency vibrational modes of [EMIN][FAP] ionic pairs has shown that the hydrogen bond formed between EMIN+ and FAP– is not strong enough to explain the relatively large stability of the ion pairs .…”

Section: Introductionmentioning

confidence: 99%

“…However, the interpretation of the vibrational spectra in terms of the atomic motions related to each observed signal can also provide valuable information about the chemical systems, its structure and behavior. 22 For example, the contribution of N−H stretching motion to the different high-frequency vibrational modes of [EMIN][FAP] ionic pairs has shown that the hydrogen bond formed between EMIN+ and FAP− is not strong enough to explain the relatively large stability of the ion pairs. 8 More recently, the interpretation of predicted Raman spectra for a number of anthraquinone dyes and lakes allowed Pagliai et al not only to confirm the structure of such compounds but also to identify some signals in the experimental Raman spectra as overtones.…”

Section: Introductionmentioning

confidence: 99%

Improving Vibrational Mode Interpretation Using Bayesian Regression

Teixeira

Cordeiro

2018

J. Chem. Theory Comput.

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To streamline the interpretation of vibrational spectra, this work introduces the use of Bayesian linear regression with automatic relevance determination as a viable approach to decompose the atomic motions along any vibrational mode as a weighted combination of displacements along chemically meaningful internal coordinates. This novel approach denominated vibrational mode automatic relevance determination (VMARD) is presented and compared with the well-established potential energy decomposition (PED) scheme. Good agreement is generally attained between the two methods. VMARD returns a decomposition of the atomic displacement using only a small number of internal coordinates, thus aiding the interpretation of the vibrational spectra. Moreover, the results show that the VMARD descriptions are resilient toward the addition of additional internal coordinates, achieving a concise description of the vibrational modes despite the use of redundant internal coordinates. Potential applications of VMARD involving the gathering of physical insights on the atomic motions along the reaction coordinate at transition state structures, as well as the improvement of theoretically predicted vibrational frequencies, are also presented under a proof-ofconcept perspective.

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On the Relevance of Considering the Intermolecular Interactions on the Prediction of the Vibrational Spectra of Isopropylamine

Cited by 8 publications

References 50 publications

FTIR Spectroscopy and DFT Calculations to Probe the Kinetics of β-Carotene Thermal Degradation

FTIR Spectroscopy and DFT Calculations to Probe the Kinetics of β-Carotene Thermal Degradation

On the correction of calculated vibrational frequencies for the effects of the counterions — α,ω-diamine dihydrochlorides

Improving Vibrational Mode Interpretation Using Bayesian Regression

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