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Exciton coupling between enones: Quassinoids revisited
Author(s) -
Pescitelli Gennaro,
Di Bari Lorenzo
Publication year - 2017
Publication title -
chirality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.43
H-Index - 77
eISSN - 1520-636X
pISSN - 0899-0042
DOI - 10.1002/chir.22711
Subject(s) - exciton , chemistry , degenerate energy levels , enone , chromophore , chirality (physics) , circular dichroism , coupling (piping) , molecular physics , physics , quantum mechanics , photochemistry , crystallography , stereochemistry , chiral anomaly , mechanical engineering , nambu–jona lasinio model , engineering , fermion
The electronic circular dichroism (ECD) spectra of two previously reported quassinoids containing a pair of enone chromophores are revisited to gain insight into the consistency and applicability of the exciton chirality method. Our study is based on time‐dependent Density Functional Theory calculations, transition and orbital analysis, and numerical exciton coupling calculations. In quassin ( 1 ) the enone/enone exciton coupling is quasi‐degenerate, yielding strong rotational strengths that account for the observed ECD spectrum in the enone π‐π* region. In perforalactone C ( 2 ) the nondegenerate coupling produces weak rotational strengths, and the ECD spectrum is dominated by other mechanisms of optical activity. We remark the necessity of a careful application of the nondegenerate exciton coupling method in similar cases.