Exciton coupling between enones: Quassinoids revisited. Issue 9 (21st June 2017)

• Record Type: Journal Article
• Authors: Pescitelli, Gennaro; Di Bari, Lorenzo
• Is Part Of: Chirality. Volume 29:Issue 9(2017)
• Page Start: 476
• Page End: 485
• Publication Date: 2017-06-21
• Subjects: absolute configuration -- electronic circular dichroism -- exciton chirality method -- natural products -- TDDFT calculations; Chirality -- Periodicals; Pharmaceutical chemistry -- Periodicals; 541.22
• DOI: 10.1002/chir.22711
• Languages: English
• ISSNs: 0899-0042

Abstract

Abstract: 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. Abstract :