The vibrational CD spectra of propylene oxide in liquid xenon: a proof-of-principle CryoVCD study that challenges theory

Kreienborg, Nora M.; Bloino, Julien; Osowski, Tobias; Pollok, Corina H.; Merten, Christian

doi:10.1039/c9cp00537d

Cited by 20 publications

(43 citation statements)

References 31 publications

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“…The spectra generated with the anharmonic constants at the B3PW91/jun-cc-pVTZ were inverted (intensity multiplied by −1) to make the difference with B3PW91/SNSD more visible. experimental setup, only the fingerprint region is available with a high level of confidence and used here as reference (Merten et al, 2013;Kreienborg et al, 2019). Some larger differences can be observed between the levels of theory, especially in the pattern around 1500 cm −1 .…”

Section: Phase Iii: Spectral Band-shapesmentioning

confidence: 99%

Accuracy and Reliability in the Simulation of Vibrational Spectra: A Comprehensive Benchmark of Energies and Intensities Issuing From Generalized Vibrational Perturbation Theory to Second Order (GVPT2)

Yang

Mendolicchio

Barone

et al. 2021

Front. Astron. Space Sci.

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Vibrational spectroscopy represents an active frontier for the identification and characterization of molecular species in the context of astrochemistry and astrobiology. As new missions will provide more data over broader ranges and at higher resolution, especially in the infrared region, which could be complemented with new spectrometers in the future, support from laboratory experiments and theory is crucial. In particular, computational spectroscopy is playing an increasing role in deepening our understanding of the origin and nature of the observed bands in extreme conditions characterizing the interstellar medium or some planetary atmospheres, not easily reproducible on Earth. In this connection, the best compromise between reliability, feasibility and ease of interpretation is still a matter of concern due to the interplay of several factors in determining the final spectral outcome, with larger molecular systems and non-covalent complexes further exacerbating the dichotomy between accuracy and computational cost. In this context, second-order vibrational perturbation theory (VPT2) together with density functional theory (DFT) has become particularly appealing. The well-known problem of the reliability of exchange-correlation functionals, coupled with the treatment of resonances in VPT2, represents a challenge for the determination of standardized or “black-box” protocols, despite successful examples in the literature. With the aim of getting a clear picture of the achievable accuracy and reliability of DFT-based VPT2 calculations, a multi-step study will be carried out here. Beyond the definition of the functional, the impact of the basis set and the influence of the resonance treatment in VPT2 will be analyzed. For a better understanding of the computational aspects and the results, a short summary of vibrational perturbation theory and the overall treatment of resonances for both energies and intensities will be given. The first part of the benchmark will focus on small molecules, for which very accurate experimental and theoretical data are available, to investigate electronic structure calculation methods. Beyond the reliability of energies, widely used for such systems, the issue of intensities will also be investigated in detail. The best performing electronic structure methods will then be used to treat larger molecular systems, with more complex topologies and resonance patterns.

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Section: Phase Iii: Spectral Band-shapesmentioning

confidence: 99%

Accuracy and Reliability in the Simulation of Vibrational Spectra: A Comprehensive Benchmark of Energies and Intensities Issuing From Generalized Vibrational Perturbation Theory to Second Order (GVPT2)

Yang

Mendolicchio

Barone

et al. 2021

Front. Astron. Space Sci.

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“…These calculations usually require a comprehensive conformational analysis that finds all important conformers prior to computing the vibrational spectra. Here, classical hybrid DFT functionals such as B3LYP or B3PW91 are still superior in performance in terms of both intensities and frequencies (in both the scaled harmonic and anharmonic cases, ), and outperform more modern functionals such as the Minnesota series . Including dispersion corrections usually does not change the single conformer spectra, but may affect structures and thermochemistry.…”

Section: Absolute Configurations From Vcd Spectroscopymentioning

confidence: 99%

“…[4] There are no empirical rules for VCD spectra interpretations, which prevents the qualitative prediction of VCD signs even when the investigated molecule features only one conformation. [5] Consequently, the analysis of a VCD spectrum, targeting, for instance, the determination of an unknown absolute configuration (AC), [6] is inextricably connected to density functional theory (DFT) based spectra predictions. Computed IR and VCD spectra typically match pretty well with the experimental data.…”

Section: Introductionmentioning

confidence: 99%

“…Consequently, in contrast to the well‐known electronic CD, which requires specific UV/Vis active chromophores, VCD spectra can be obtained for all non‐racemic molecules – even for those being chiral only due to isotopic labeling . There are no empirical rules for VCD spectra interpretations, which prevents the qualitative prediction of VCD signs even when the investigated molecule features only one conformation . Consequently, the analysis of a VCD spectrum, targeting, for instance, the determination of an unknown absolute configuration (AC), is inextricably connected to density functional theory (DFT) based spectra predictions.…”

Section: Introductionmentioning

confidence: 99%

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Recent Advances in the Application of Vibrational Circular Dichroism Spectroscopy for the Characterization of Asymmetric Catalysts

Merten

2020

Eur J Org Chem

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In this Minireview, we summarize our recent efforts to use vibrational circular dichroism (VCD) spectroscopy, the chiroptical version of IR spectroscopy, for the characterization of conformational preferences of asymmetric catalysts and complexes, formed upon the respective interactions or reactions of catalysts with substrates. After giving a brief overview of the general aspects of the technique, we showcase how VCD spectra of a chiral ion-pairing catalyst could be used to confirm a conformational shifting mechanism that determines the enan-[a]

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“…Its rigid structure makes it an ideal candidate for study by vibrational spectroscopy. [4][5][6][7] Solvation of PO has been studied using vibrational circular dichroism (VCD) and optical rotatory dispersion (ORD) to understand hydrogen bonding with chiral molecules. [8] In this work, we have studied PO hydration to PG in pure water.…”

Section: Introductionmentioning

confidence: 99%

Chirality Retention in Aqueous Propylene Oxide Hydration: Chirality of the Transition State

Shukla¹,

Yu²,

Pradhan³

et al. 2021

Israel Journal of Chemistry

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The hydration kinetics of enantiomerically pure propylene oxide (PO, CH 3 *CHCH 2 O) to chiral propylene glycol (PG, CH 3 *CH(OH)CH 2 OH) in aqueous solution have been studied using FTIR while simultaneously monitoring the net chirality of the reaction mixture. The hydration reaction appears to be first-order in the PO concentration with a rate constant of k ffi0.05 hr À 1 . More importantly, the reaction is enantioselective; the product PG retains the chirality of the 2C carbon in PO with ~2 : 1 selectivity. The fact that there is some inversion of the chirality suggests that the dominant transition state is one in which the 2CÀ O bond in PO is cleaved, resulting in a close to planar transition state capable of inversion during hydration. If the transition state involved 1CÀ O cleavage it would retain the rigid chiral center of the PO reactant, preventing significant inversion.

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The vibrational CD spectra of propylene oxide in liquid xenon: a proof-of-principle CryoVCD study that challenges theory

Cited by 20 publications

References 31 publications

Accuracy and Reliability in the Simulation of Vibrational Spectra: A Comprehensive Benchmark of Energies and Intensities Issuing From Generalized Vibrational Perturbation Theory to Second Order (GVPT2)

Accuracy and Reliability in the Simulation of Vibrational Spectra: A Comprehensive Benchmark of Energies and Intensities Issuing From Generalized Vibrational Perturbation Theory to Second Order (GVPT2)

Recent Advances in the Application of Vibrational Circular Dichroism Spectroscopy for the Characterization of Asymmetric Catalysts

Chirality Retention in Aqueous Propylene Oxide Hydration: Chirality of the Transition State

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