Interplay of Stereoelectronic and Vibrational Modulation Effects in Tuning the UPS Spectra of Unsaturated Hydrocarbon Cage Compounds

Paoloni, Lorenzo; Fusè, Marco; Baiardi, Alberto; Barone, Vincenzo

doi:10.1021/acs.jctc.0c00645

Cited by 1 publication

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“…So, once again, the synthesis and availability of appropriate compounds have been demonstrated to be quite valuable for elucidating the electronic effect through chiroptical spectroscopies. We think that this adds a small independent contribution to research on the homoconjugation phenomenon, which is still receiving attention via both new experiments and theories [38,39].…”

Section: Discussionmentioning

confidence: 95%

Vibrational Circular Dichroism Detects Symmetry Breaking due to Conformational Mobility in C2-Symmetry Chiral Molecules and Provides Further Insight into Inter-Chromophoric Interactions

et al. 2020

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Bicyclo[3.3.1]nonane-2,6-dione (1) and bicyclo[3.3.1]nona-3,7-diene-2,6-dione (2) have been examined by vibrational circular dichroism (VCD), which, as for most C2-symmetric systems, exhibits strong VCD signals. In the case of 2, VCD signals are stronger and sharper with several bisignate doublets; for 1, signals are less intense and broader. The VCD and IR spectra are excellently predicted by DFT calculations: only one conformer is present for 2, while for 1, three main conformers, related through concerted skeleton torsional motions are present (two of them being interchanged by C2-rotation). The VCD spectrum shows specific features for the different conformers, such that correct population factors are crucial for reproducing experimental data. Also, the TD-DFT prediction of ECD (electronic circular dichroism) spectra is good. By comparing the spectroscopic signature of the two molecules (both VCD and ECD) and by careful analysis of the theoretical results, the role of the C=C double bond in compound (2) is evidenced. The double bond contributes toward enhancing the CD response both electronically and vibrationally.

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Section: Discussionmentioning

confidence: 95%