TY - JOUR
T1 - Individual scale factor approach for the vibrational circular dichroism similarity-guided spectral and conformational analysis of perezone and dihydroperezone
AU - Muñoz, Marcelo A.
AU - Burgueño-Tapia, Eleuterio
AU - Joseph-Nathan, Pedro
N1 - Publisher Copyright:
© 2022 Wiley Periodicals LLC.
PY - 2023/1
Y1 - 2023/1
N2 - Evaluation of DFT calculated vibrational parameters for the IR and VCD spectra similarity of perezone (1) and dihydroperezone (2) was undertaken. Conformational sets were obtained using different search engines, and the parameters needed for spectra prediction were obtained using several combinations of commonly employed functionals and basis sets, and then weighted spectra were generated and compared with observed traces to provide infrared similarity (SIR) and enantiomeric similarity index (ESI) values. These values evidenced a poor performance of the evaluated levels of theory that were overcome when using the individual scaling factors approach, providing 16% to 139% increases of the ESI values. The best performing level of theory was the B3LYP/DGDZVP2 with ESI values of 0.722 and 0.792 for 1 and 2. Moreover, a correlation analysis showed that the irregular DFT performance arises from rotational strength deviations, which suggests to discard conformational abundance accuracy as the main source of differences. Furthermore, a similarity guided conformational analysis showed that conformations with high ESI values prefer particular orientations of the CC bonds directly attached to the stereogenic carbon atom, with more distant dihedral angles having less influence. Additionally, folded and extended conformers appear to be equally capable to yield high individual ESI values, although abundances of folded conformers just account for 16% of the total population. Nevertheless, abundance optimization showed that a high ESI similarity value of 0.834, is possible when the population of these conformers is increased to 26%, suggesting that a larger abundance of these conformers might be present in solution.
AB - Evaluation of DFT calculated vibrational parameters for the IR and VCD spectra similarity of perezone (1) and dihydroperezone (2) was undertaken. Conformational sets were obtained using different search engines, and the parameters needed for spectra prediction were obtained using several combinations of commonly employed functionals and basis sets, and then weighted spectra were generated and compared with observed traces to provide infrared similarity (SIR) and enantiomeric similarity index (ESI) values. These values evidenced a poor performance of the evaluated levels of theory that were overcome when using the individual scaling factors approach, providing 16% to 139% increases of the ESI values. The best performing level of theory was the B3LYP/DGDZVP2 with ESI values of 0.722 and 0.792 for 1 and 2. Moreover, a correlation analysis showed that the irregular DFT performance arises from rotational strength deviations, which suggests to discard conformational abundance accuracy as the main source of differences. Furthermore, a similarity guided conformational analysis showed that conformations with high ESI values prefer particular orientations of the CC bonds directly attached to the stereogenic carbon atom, with more distant dihedral angles having less influence. Additionally, folded and extended conformers appear to be equally capable to yield high individual ESI values, although abundances of folded conformers just account for 16% of the total population. Nevertheless, abundance optimization showed that a high ESI similarity value of 0.834, is possible when the population of these conformers is increased to 26%, suggesting that a larger abundance of these conformers might be present in solution.
KW - VISSAT
KW - absolute configuration
KW - chiroptical spectroscopy
KW - natural product
KW - software
UR - http://www.scopus.com/inward/record.url?scp=85142236394&partnerID=8YFLogxK
U2 - 10.1002/chir.23517
DO - 10.1002/chir.23517
M3 - Artículo
C2 - 36398355
AN - SCOPUS:85142236394
SN - 0899-0042
VL - 35
SP - 67
EP - 79
JO - Chirality
JF - Chirality
IS - 1
ER -