Chiral Molecular Structure Determination for a Desired Compound Just from Its Molecular Formula and Vibrational Optical Activity Spectra

Abstract

A novel proof-of-concept model for chiral molecular structure determination using just the molecular formula and vibrational optical activity (VOA) spectra is presented. To verify this concept, the molecular formula of a desired compound is used to generate all possible chiral structural isomers and their VOA spectra are predicted. The similarity analyses of predicted VOA spectra were then carried out in two different ways: (a) similarity between VOA spectrum of one structural isomer with those of the rest, referred to as cross-correlations; (b) similarity between VOA spectra of all chiral structural isomers with the experimental VOA spectra of the desired compound. Three different molecular formulae, C 4 H 8 O, C 3 H 5 ClO, and C 6 H 10 O, and their chiral structural isomers (6, 9, and 75 respectively), were investigated. In each case, the correct chiral molecular structure of the desired compound was identified without ambiguity. Cross-correlation analysis revealed the uniqueness of VOA spectra in deducing the chiral molecular structure solely from its molecular formula. Different chiral structural isomers associated with the molecular formula CH 3 NO 2 were also found to have no significant cross-correlations between their VOA spectra, opening a pathway to detect and identify the elusive chiral Nhydroxyoxaziridine from its VOA spectra.

Vibrational Raman optical activity of diacetyl L‐tartaric acid and corresponding surfactants: Sodium salts and shorter analogs of surfactants simplify the interpretations

“…However, it should be noted that one may claim satisfactory correlation between experimental and predicted ROA/CID spectra by visual perusal of positive/negative features, but quantitative analyses contradict such visual perceptions, as indicated by the similarity overlap values of Sim Raman (0.74), Sim ROA (0.13), and Sim CID (0.32). As stated in previous works, [ 43,44 ] Sim values less than 0.4 do not suggest a good correspondence between experimental and predicted spectra. Although Sim Raman value is greater than 0.4, Raman spectra being monosignate are less discerning than positive and negative peaks containing Sim ROA and Sim CID.…”

“…The magnitudes of Sim ROA and Sim CID values are larger than the minimum recommended value of 0.4. [ 43,44 ] Based on both visual and quantitative comparisons, one can comfortably conclude that the experimental ROA spectra of DATNa in water are satisfactorily reproduced by PCM calculations, in contrast to the earlier noted failure for DAT. This observation supports our assertion stated early on.…”

“…For the equations, and attributes, of the similarity overlap parameters, see previous publications. [ 14,43,44 ] Although the spectral overlaps for different regions, namely, 225–1,800, 225–1,500, and 430–1,500 cm −1 , were examined, the conclusions are not influenced by the choice of the region, so only the latter are presented for discussion in this manuscript.…”

Chiroptical spectroscopic studies for the absolute configuration determination of hexahydrocurcumin and octahydrocurcumin

“…The maximum Sim VCD value is +0.548, and the maximum Sim VDF value is +0.588. These values are larger than the recommended reliability threshold of 0.4, 47,48 leading to a confident assignment of (−)‐( R )‐HHC.…”

“…The maximum SimVCD value is +0.548, and the maximum SimVDF value is +0.588. These values are larger than the recommended reliability threshold of 0.4, 47,48 leading to a confident assignment of (À)-(R)-HHC. The dominant feature in the predicted VCD spectrum is the bisignate feature, negative at 1269 and positive at 1251 cm À1 .…”