On Raman optical activity sign-switching between the ground and excited states leading to an unusual resonance ROA induced chirality

Abstract

Raman optical activity (ROA) spectra recorded for a chiral naphthalene diimide derivative (nBu-NDI-BINAM) dissolved in a series of solvents exhibit strong solute to solvent induced chirality with: (1) dominating bands...

Can One Measure Resonance Raman Optical Activity?

“…The comparisons shown in Figure 3 clearly demonstrate that one can explain the experimental observation reported in Ref. [12] satisfactorily with the eCP‐Raman mechanism, and not by natural RROA.…”

“…In light of these findings, we focus on interpretation of experimental I R − I L features of three chiral solutes (shown in Figure 1) under resonance, which were previously regarded as RROA. These are two transition metal complexes, R ‐ Ni [20] and R ‐ Cu , [5] and one organic molecule, S ‐ BN [12] . These systems show both multi‐signate and mono‐signate I R − I L patterns.…”

“…These systems show both multi‐signate and mono‐signate I R − I L patterns. Although some interpretations were presented before, based on the SES theory, [5, 12] no theoretical simulations of the spectra were reported.…”

“…Using experimental ECD profiles in two different solvents, CHCl 3 and CH 3 CN, and the experimental concentration information reported in Ref. [12], we performed similar calculations as for Ni and Cu . The final I R − I L simulations of S ‐ BN in CHCl 3 and CH 3 CN are summarized in Figure 3, for comparison to the experimental data.…”

“… a) Comparison of the experimental [12] (top) and simulated (bottom) I R − I L (eCP‐Raman) spectra of the chiral solute S ‐ BN whose bands are shown in the rectangle box and their intensities amplified by a factor of ten, and of achiral solvent CHCl 3 whose bands are those outside the box. b) Parallel plots as in (a) but with S ‐ BN in CH 3 CN solution.…”