Assignment of the Molecular Absolute Configuration through the ab Initio Hartree−Fock Calculation of the Optical Rotation:  Can the Circular Dichroism Data Help in Reducing Basis Set Requirements?†

2003 ◽  
Vol 68 (13) ◽  
pp. 5186-5192 ◽  
Author(s):  
Egidio Giorgio ◽  
Camilla Minichino ◽  
Rosario G. Viglione ◽  
Riccardo Zanasi ◽  
Carlo Rosini
Keyword(s):  
Circular Dichroism ◽  
Ab Initio ◽  
Absolute Configuration ◽  
Optical Rotation ◽  
Basis Set ◽  
Hartree Fock ◽  
Circular Dichroism Data ◽  
Circular Dichroïsm

scholarly journals Absolute Configuration Sensing of Chiral Aryl- and Aryloxy-Propionic Acids by Biphenyl Chiroptical Probes

Chemosensors ◽  
2021 ◽  
Vol 9 (7) ◽  
pp. 154
Author(s):  
Stefania Vergura ◽  
Stefano Orlando ◽  
Patrizia Scafato ◽  
Sandra Belviso ◽  
Stefano Superchi
Keyword(s):  
Circular Dichroism ◽  
Absolute Configuration ◽  
Optical Rotation ◽  
Environmental Pollutants ◽  
Red Shift ◽  
Electronic Circular Dichroism ◽  
Configuration Assignment ◽  
Clear Sign ◽  
The Absolute ◽  
Circular Dichroïsm

The absolute configuration of chiral 2-aryl and 2-aryloxy propionic acids, which are among the most common chiral environmental pollutants, has been readily and reliably established by either electronic circular dichroism spectroscopy or optical rotation measurements employing suitably designed 4,4′-disubstituted biphenyl probes. In fact, the 4,4′-biphenyl substitution gives rise to a red shift of the diagnostic electronic circular dichroism signal of the biphenyl A band employed for the configuration assignment, removing its overlap with other interfering dichroic bands and allowing its clear sign identification. The largest A band red shift, and thus the most reliable results, are obtained by employing as a probe the 4,4′-dinitro substituted biphenylazepine 3c. The method was applied to the absolute configuration assignment of 2-arylpropionic acids ibuprofen (1a), naproxen (1b), ketoprofen (1c) and flurbiprofen (1d), as well as to the 2-aryloxypropionic acids 2-phenoxypropionic acid (2a) and 2-naphthoxypropionic acid (2b). This approach, allowing us to reveal the sample’s absolute configuration by simple optical rotation measurements, is potentially applicable to online analyses of both the enantiomeric composition and absolute configuration of these chiral pollutants.

scholarly journals Absolute Configuration Determination by Quantum Mechanical Calculation of Chiroptical Spectra: Basics and Applications to Fungal Metabolites

2018 ◽  
Vol 25 (2) ◽  
pp. 287-320 ◽  
Author(s):  
Stefano Superchi ◽  
Patrizia Scafato ◽  
Marcin Gorecki ◽  
Gennaro Pescitelli
Keyword(s):  
Natural Products ◽  
Circular Dichroism ◽  
Absolute Configuration ◽  
Optical Rotation ◽  
Computational Approach ◽  
Quantum Mechanical ◽  
Fungal Metabolites ◽  
Common Technique ◽  
The Absolute ◽  
Circular Dichroïsm

Background: Quantum mechanical simulations of chiroptical properties, such as electronic circular dichroism (ECD), optical rotation (OR), and vibrational circular dichroism (VCD), have rapidly become very popular to assign the absolute configuration of novel natural products. Objective: We review the application of the ECD/OR/VCD computational methodology to chiral metabolites of fungal origin. First, we summarize the fundamentals of the three spectroscopies; then, we focus on the specific experimental and computational issues allied to the application of their calculations. Methods: We surveyed the entire literature describing the use of ECD/OR/VCD computations for fungal metabolites, and catalogued all papers according to the method employed and to the structural family of compounds. Then, we chose several examples to illustrate the use of the techniques and highlight the practical application of the computational approach. Results: Our literature survey demonstrates that the simulation of ECD/OR/VCD spectra is nowadays widespread and accessible also to non-experts, although a good computational practice is necessary to avoid wrong assignments. ECD is still the most common technique used in the context of fungal metabolites. OR and VCD may be profitably employed when the compound of interest lacks chromophoric groups. Our examples illustrate that the combination of two or more chiroptical methods is strongly advisable in some cases, especially in the presence of high conformational flexibility, where a single technique does not lead to a safe conclusion. Conclusion: The ECD/OR/VCD computational approach is a reliable and versatile method to assign the absolute configuration of fungal metabolites and related natural products.

A conformational study of (1S, 2R, 5S)-( + )-menthol using vibrational circular dichroism spectroscopy

1998 ◽  
Vol 76 (3) ◽  
pp. 274-283 ◽  
Author(s):  
Jennifer L McCann ◽  
Arvi Rauk ◽  
Hal Wieser
Keyword(s):  
Circular Dichroism ◽  
Density Functional ◽  
Chair Conformation ◽  
Equilibrium Mixture ◽  
Vibrational Circular Dichroism ◽  
Basis Set ◽  
Hydroxyl Group ◽  
Functional Theory ◽  
Hartree Fock ◽  
Circular Dichroïsm

We report the experimental and predicted absorption and vibrational circular dichroism (VCD) spectra of (1S, 2R, 5S)-(+)-menthol. The harmonic force fields and atomic polar tensors (APTs) were obtained for 10 conformers using density functional theory (DFT) with the Becke3LYP functional and the 6-31G** basis set. The atomic axial tensors (AATs) were obtained with restricted Hartree-Fock (RHF) theory and a 6-31G basis set. VCD intensities were predicted from vibronic coupling theory (VCT). The predicted absorption and VCD spectra based on an equilibrium mixture of conformers corresponded well with the experimental spectra, indicating a reasonable geometry and frequency analysis for each of the conformers. The largest contributions towards the equilibrium population derive from conformers in which the cyclohexane ring occupies a chair conformation, the isopropyl group is directed away from the hydroxyl group, and only the hydroxyl group assumes different conformations.Key words: vibrational circular dichroism (VCD), menthol, conformational analysis.

Local and framework stereochemical markers in vibrational circular dichroism: 1,2- and 2,3-dimethylaziridines

1993 ◽  
Vol 71 (12) ◽  
pp. 2028-2037 ◽  
Author(s):  
Danya Yang ◽  
Thomas Eggimann ◽  
Hal Wieser ◽  
Arvi Rauk ◽  
Gennadii Shustov
Keyword(s):  
Circular Dichroism ◽  
Absolute Configuration ◽  
Vibrational Circular Dichroism ◽  
Basis Set ◽  
Wave Number ◽  
Number Range ◽  
The Absolute ◽  
Absolute Magnitudes ◽  
Almost All ◽  
Circular Dichroïsm

The vibrational circular dichroism (VCD) spectra of 2,3-dimethylaziridine 1 and 1,2-dimethylaziridine 2 were measured experimentally and interpreted with the help of ab initio Vibronic Coupling Theory (VCT) both in the common origin (CO) and distributed origin (DO) gauge. The absolute magnitudes of the VCD intensities by the VCT-CO method in the mid-IR range are closer to the experimental measurement. Both VCT-DO and VCT-CO methods, however, predict the same signs for almost all VCD bands. In general, both VCT-DO and VCT-CO methods predict VCD and IR spectra that are both in good agreement with the experimental spectra. The VCT method together with the 6-31G*(0.3) basis set can be employed with confidence in determining the absolute configuration of a chiral molecule. The theoretical and experimental VCD spectra of 1 and 2 were compared with the VCD spectra of the isostructural 2,3-dimethyloxirane and -thiirane. One of the Me rocking motions, in the wave number range 1050–1150 cm−1, was found to serve as a possible marker for the stereochemistry of the molecular skeleton. Two other modes were identified whose Cotton effects (CEs) are characteristic of the local asymmetry, and for which chirality rules were proposed. The first is a methyne vibration, ||CH, which is expected to have a (−) CE at a three-ring centre with (R) absolute configuration. The second is an umbrella motion of a methyl group, which is expected to have a (+) CE when attached to a three-ring centre with (R) absolute configuration.

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