title: A single chiroptical spectroscopic method may not be able to establish the absolute configurations of diastereomers: dimethylesters of hibiscus and garcinia acids.
abstract: Electronic circular dichroism (ECD), optical rotatory dispersion (ORD), and vibrational circular dichroism (VCD) spectra of hibiscus acid dimethyl ester have been measured and analyzed in combination with quantum chemical calculations of corresponding spectra. These results, along with those reported previously for garcinia acid dimethyl ester, reveal that none of these three (ECD, ORD, or VCD) spectroscopic methods, in isolation, can unequivocally establish the absolute configurations of diastereomers. This deficiency is eliminated when a combined spectral analysis of either ECD and VCD or ORD and VCD methods is used. It is also found that the ambiguities in the assignment of absolute configurations of diastereomers may also be overcome when unpolarized vibrational absorption is included in the spectral analysis.
authors.affiliation: Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37235, USA. Prasad.L.Polavarapu@vanderbilt.edu
authors.forename: Prasad L
authors.initials: PL
authors.lastname: Polavarapu
authors.forename: Emily A
authors.initials: EA
authors.lastname: Donahue
authors.forename: Ganesh
authors.initials: G
authors.lastname: Shanmugam
authors.forename: Giovanni
authors.initials: G
authors.lastname: Scalmani
authors.forename: Edward K
authors.initials: EK
authors.lastname: Hawkins
authors.forename: Carmelo
authors.initials: C
authors.lastname: Rizzo
authors.forename: Ibrahim
authors.initials: I
authors.lastname: Ibnusaud
authors.forename: Grace
authors.initials: G
authors.lastname: Thomas
authors.forename: Deenamma
authors.initials: D
authors.lastname: Habel
authors.forename: Dellamol
authors.initials: D
authors.lastname: Sebastian
mesh_terms: D002942:Circular Dichroism; D002951:Citrates / Q000737:chemistry*; D004952:Esters / Q000737:chemistry*; D031584:Hibiscus / Q000737:chemistry*; D008968:Molecular Conformation; D011789:Quantum Theory; D013237:Stereoisomerism; D014732:Vibration
chemical_list: D002951:Citrates; D004952:Esters; C007999:hydroxycitric acid