Vibrational Raman optical activity of bicyclic terpenes: comparison between experimental and calculated vibrational Raman, Raman optical activity, and dimensionless circular intensity difference spectra and their similarity analysis

Polavarapu, Prasad L.; Covington, Cody L.; Chruszcz‐Lipska, Katarzyna; Zając, Grzegorz; Barańska, Małgorzata

doi:10.1002/jrs.5035

Cited by 12 publications

(14 citation statements)

References 38 publications

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“…When f(x) and g(x), in equations –, both represent simulated QC predicted spectra, say, for two different diastereomers, then we identify the resulting overlap as cross‐correlation …”

Section: Program Descriptionmentioning

confidence: 99%

“…When this methodology is extended to VROA and corresponding Raman spectra, their ratio is called the dimensionless circular intensity difference (CID) spectrum, and is defined as:

normalΔ ((),, \overset{true¯}{ν}) = ({,, \begin{matrix} center \\ center \frac{I_{α}^{γ} (\overset{ν}{true}) - I_{β}^{δ} (\overset{ν}{true})}{I_{α}^{γ} (\overset{ν}{true}) + I_{β}^{δ} (\overset{ν}{true})} \\ center \\ center 0 \end{matrix} \begin{matrix} center \\ center, \\ center \\ center, \end{matrix} \begin{matrix} center \\ center if \frac{(||,, I_{α}^{γ} ((),, \overset{true¯}{ν}) - I_{β}^{δ} ((),, \overset{true¯}{ν}))}{I_{α}^{γ} (\overset{ν}{true}) + I_{β}^{δ} (\overset{ν}{true})} > T_{c} and I_{α}^{γ} (\overset{ν}{true}) + I_{β}^{δ} (\overset{ν}{true}) > τ_{R} \\ center \\ center Otherwise \end{matrix})

…”

Section: Program Descriptionmentioning

confidence: 99%

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CDSpecTech: A single software suite for multiple chiroptical spectroscopic analyses

Covington

Polavarapu

2017

Chirality

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The program CDSpecTech was developed to facilitate the analysis of chiroptical spectra, which include the following: vibrational circular dichroism (VCD) and corresponding vibrational absorption (VA) spectra; vibrational Raman optical activity (VROA) and corresponding vibrational Raman spectra; electronic circular dichroism (ECD) and corresponding electronic absorption (EA) spectra. In addition, the program allows for generating optical rotatory dispersion (ORD) as the Kramers-Kronig transform of ECD spectra. The simulation of theoretical spectra from transition strengths can be achieved using different bandshape profiles. The experimental and simulated theoretical spectra can be visually compared by displaying them together. A unique feature of CDSpecTech is performing spectral analysis using the ratio spectra; i.e., the dimensionless dissymmetry factor (DF) spectrum, which is the ratio of CD to absorption spectra, and the dimensionless circular intensity difference (CID) spectrum, which is the ratio of VROA to vibrational Raman spectra. The quantitative agreement between experimental and simulated theoretical spectra can also be assessed from the numerical similarity overlap between them. Two different similarity overlap methods are available. The program uses a graphical user interface which allows for ease of use and facilitates the analysis. All these features make CDSpecTech a valuable tool for the analysis of chiroptical spectra. The program is freely available on the World Wide Web.

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“…When f(x) and g(x), in equations –, both represent simulated QC predicted spectra, say, for two different diastereomers, then we identify the resulting overlap as cross‐correlation …”

Section: Program Descriptionmentioning

confidence: 99%

“…When this methodology is extended to VROA and corresponding Raman spectra, their ratio is called the dimensionless circular intensity difference (CID) spectrum, and is defined as:

normalΔ ((),, \overset{true¯}{ν}) = ({,, \begin{matrix} center \\ center \frac{I_{α}^{γ} (\overset{ν}{true}) - I_{β}^{δ} (\overset{ν}{true})}{I_{α}^{γ} (\overset{ν}{true}) + I_{β}^{δ} (\overset{ν}{true})} \\ center \\ center 0 \end{matrix} \begin{matrix} center \\ center, \\ center \\ center, \end{matrix} \begin{matrix} center \\ center if \frac{(||,, I_{α}^{γ} ((),, \overset{true¯}{ν}) - I_{β}^{δ} ((),, \overset{true¯}{ν}))}{I_{α}^{γ} (\overset{ν}{true}) + I_{β}^{δ} (\overset{ν}{true})} > T_{c} and I_{α}^{γ} (\overset{ν}{true}) + I_{β}^{δ} (\overset{ν}{true}) > τ_{R} \\ center \\ center Otherwise \end{matrix})

…”

Section: Program Descriptionmentioning

confidence: 99%

CDSpecTech: A single software suite for multiple chiroptical spectroscopic analyses

Covington

Polavarapu

2017

Chirality

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“…For (1S,4R)‐(+)‐fenchone, the C=O stretching mode (at 1,793 cm −1 in B3LYP/aug‐cc‐pVDZ and 1,813 cm −1 in B3PW91/aug‐cc‐pVDZ) is predicted to have

∣ δ_{k}^{2} ∣ > (||, 3 γ_{k}^{2})

(Table S5). The positive experimental VROA observed for this band at ~1,740 cm −1 is weak, but the observed sign is reproduced in the simulated spectrum from

δ_{k}^{2}

contribution but not in simulated spectrum from

γ_{k}^{2}

contribution (Figure S4). A lower wavenumber mode (232 cm −1 in B3LYP/aug‐cc‐pVDZ calculation and 228 cm −1 in B3PW91/aug‐cc‐pVDZ calculation) also has

∣ δ_{k}^{2} ∣ > ∣ 3 γ_{k}^{2} ∣

.…”

Section: Resultsmentioning

confidence: 99%

“…Therefore, in order for

ω^{- 1} δ_{k}^{2}

to be dominant, the magnitude of

ω^{- 1} δ_{k}^{2}

itself should be at least three times larger than that of

ω^{- 1} γ_{k}^{2}

, especially for situations where a 4

ω^{- 1} γ_{k}^{2}

and a 5

ω^{- 1} δ_{k}^{2}

terms have opposite signs. Polavarapu et al have investigated the SCP backscattering VROA spectra of five terpenes and displayed the simulated spectra using the following equations for VROA activities, P k, and Raman activities, S k :

P_{k} = \frac{2 π}{λ} \times 16 \times ((), 3 ω^{- 1} γ_{k}^{2} + ω^{- 1} δ_{k}^{2}) = P_{k} ((), γ_{k}^{2}) + P_{k} ((), δ_{k}^{2}),

S_{k} = 2 \times ((), 45 {\overset{false¯}{α}}_{k}^{2} + 7 β_{k}^{2}) .

…”

Section: Introductionmentioning

confidence: 99%

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Vibrational Raman optical activity of camphor: The importance of electric‐dipole—electric‐quadrupole polarizability contribution

Johnson

Zając

Barańska

et al. 2020

J Raman Spectroscopy

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The importance of the electric‐dipole—electric‐quadrupole polarizability contribution to the vibrational Raman optical activity (VROA) and dimensionless circular intensity difference spectra of (1S)‐camphor is examined. The spectra are simulated with and without this tensor contribution using density functional theory calculations, and similarity is evaluated for each against the experimental spectra. Careful examination of the comparison between experimental and calculated spectra reveals multiple vibrational bands, in the ~1,130–950 cm−1 region, originating from −C–H bending vibrations that are dominated by the electric‐dipole—electric‐quadrupole polarizability contributions. The similarity overlap analysis also reveals that the similarity overlap between experimental and predicted spectra in the measured spectral range increases, by up to 12%, when electric‐dipole—electric‐quadrupole polarizability contributions are included. The negative VROA band at 1,125 cm−1 in the experimental spectrum of (1S)‐(‐)‐camphor can only be reproduced in the predicted spectra when electric‐dipole—electric‐quadrupole polarizability contribution is included. Investigations on additional molecules indicated that (a) two experimental VROA bands of (1S,4R)‐(+)‐fenchone at ~1,740 and 220 cm−1 originate from dominating electric‐dipole—electric‐quadrupole polarizability contribution and (b) the symmetric and antisymmetric ring deformation modes of dimethyloxirane have dominating electric‐dipole—electric‐quadrupole polarizability contribution. These observations establish the importance of electric‐dipole—electric‐quadrupole polarizability contribution to VROA for the first time.

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Absolute configuration of an axially chiral sulfonate determined from its optical rotatory dispersion, electronic circular dichroism, and vibrational circular dichroism spectra

et al. 2017

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The absolute configuration (AC) of an axially chiral sulfonate (aCSO), 3,5-dimethyl-2-(naphthalen-1-yl)-6-(naphthalen-1-yl)benzenesulfonate (labeled as aCSO5), was investigated using optical rotatory dispersion (ORD), electronic circular dichroism (ECD), and vibrational circular dichroism (VCD) spectroscopies. All three methods led to the same conclusion and the AC of aCSO5 is reliably determined to be (-)-(aR, aR), or conversely (+)-(aS, aS).

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Vibrational Raman optical activity of bicyclic terpenes: comparison between experimental and calculated vibrational Raman, Raman optical activity, and dimensionless circular intensity difference spectra and their similarity analysis

Cited by 12 publications

References 38 publications

CDSpecTech: A single software suite for multiple chiroptical spectroscopic analyses

CDSpecTech: A single software suite for multiple chiroptical spectroscopic analyses

Vibrational Raman optical activity of camphor: The importance of electric‐dipole—electric‐quadrupole polarizability contribution

Absolute configuration of an axially chiral sulfonate determined from its optical rotatory dispersion, electronic circular dichroism, and vibrational circular dichroism spectra

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