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.

A combined Raman optical activity and vibrational circular dichroism study on artemisinin-type products

2020 ◽  
Vol 22 (32) ◽  
pp. 18014-18024 ◽  
Author(s):  
Jonathan Bogaerts ◽  
Filip Desmet ◽  
Roy Aerts ◽  
Patrick Bultinck ◽  
Wouter Herrebout ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Circular Dichroism ◽  
Dft Calculations ◽  
Optical Activity ◽  
Density Functional ◽  
Vibrational Circular Dichroism ◽  
Front Line ◽  
Functional Theory ◽  
Raman Optical Activity ◽  
Circular Dichroïsm

Artemisinin and two of its derivatives, dihydroartemisinin and artesunate, front line drugs against malaria, were studied using Raman optical activity (ROA), vibrational circular dichroism (VCD) experiments and density functional theory (DFT) calculations.

scholarly journals Conformational Analysis in Solution of a Chiral Bisoxazoline Molecule: Vibrational Circular Dichroism Spectroscopy and Density Functional Theory Study

2011 ◽  
Vol 2011 ◽  
pp. 1-11
Author(s):  
A. Aamouche ◽  
P. J. Stephens
Keyword(s):  
Density Functional Theory ◽  
Circular Dichroism ◽  
Conformational Analysis ◽  
Density Functional ◽  
Circular Dichroism Spectroscopy ◽  
Vibrational Circular Dichroism ◽  
Kcal Mole ◽  
Functional Theory ◽  
High Degree ◽  
Circular Dichroïsm

The conformations of the chiral bisoxazoline: 2,2′-methylenebis[3a,8a-dihydro-8H-indeno[1,2-d]oxazole] (also named IndaBOX), have been studied. Density functional theory (DFT) calculations identify four inequivalent stable conformations. Two, I and II have, C2 symmetry; two, III and IV, have C1 symmetry. The electronic energies of I–IV are ordered: I<II<III<IV. The span in energy is <1.0 kcal/mole. Vibrational unpolarised absorption and circular dichroism spectra have been predicted for the four conformations using DFT. Comparison of population-weighted spectra to experimental spectra of CHCl3 and CDCl3 solutions in mid-IR region strongly supports the DFT predictions of the number, structures, and relative energies of the conformations of IndaBOX. This shows that DFT predicts spectra with a high degree of reliability. We will undoubtedly illustrate the advantage added by vibrational circular dichroism spectroscopy in conformational analysis and in the absolute configuration determination.

scholarly journals On the Absolute Stereochemistry of Tolterodine: A Circular Dichroism Study

2019 ◽  
Vol 12 (1) ◽  
pp. 21 ◽  
Author(s):  
Marcin Górecki ◽  
Valerio Zullo ◽  
Anna Iuliano ◽  
Gennaro Pescitelli
Keyword(s):  
Circular Dichroism ◽  
Density Functional ◽  
Vibrational Circular Dichroism ◽  
Time Dependent ◽  
Functional Theory ◽  
X Ray ◽  
Overactive Urinary Bladder ◽  
The Absolute ◽  
Circular Dichroïsm ◽  
Absolute Stereochemistry

Tolterodine (1) is a potent muscarinic receptor antagonist used in the treatment of overactive urinary bladder (OAB) syndrome. Tolterodine is chiral and it was patented, and is currently marketed, as the l-tartrate salt of the (R)-enantiomer. However, the existing literature does not offer an ultimate proof of a stereoselective mode of action of 1. A second open stereochemical issue concerns the absolute configuration (AC) of 1. Neither the original patents nor subsequent studies have established the AC of 1 in an unambiguous way, although the AC of the l-tartrate salt of 1 was assigned by X-ray diffractometry. Finally, neither electronic nor vibrational circular dichroism (ECD and VCD) spectra of 1 are reported so far. We performed a thorough ECD/VCD study of 1 in different solvents and at variable temperatures. Solvent and temperature dependence highlighted the existence of moderate flexibility which was confirmed by molecular modelling. ECD calculations with time-dependent density functional theory (TDDFT) accurately reproduced the experimental spectra and allowed us to confirm the AC of 1 in an independent way.

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