Upon DFT-D3 dispersion correction and ECD spectral confirmation, only several conformers can stably coexist for three fungal cycloaspeptides (A, D, G).
Spectrochim Acta A Mol Biomol Spectrosc
; 283: 121710, 2022 Dec 15.
Article
em En
| MEDLINE
| ID: mdl-35952587
ABSTRACT
Dispersion correction in theoretical determination of cyclopeptide conformations is emphasized. Whether in gas approximation or in solvation simulation, the density functional theory with London dispersion correction (DFT-D3) demonstrates that only 2-3 conformers can stably coexist for cycloaspeptides (A, D, G) at B3LYP-D3 and CAM-B3LYP-D3. Conformational rationality is confirmed by electronic circular dichroism (ECD). Whether for Cotton effect or for excitation energy, TD-B3LYP-D3 has better performances than TD-CAM-B3LYP-D3 because the former can better reproduce the experiment. A molecular orbital analysis is used to interpret ECD, where two energy bands observed in experiment originates from the ππ* transitions other than the σπ* transitions. Long-range correction and solvent effect make H-bonds shorten, and dispersion correction makes them further shorten.
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Eletrônica
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En
Ano de publicação:
2022
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Article