Previously, we and other laboratories have reported an unusual and strong Raman optical activity (ROA) induced in solvents by chiral dyes. Various theories of the phenomenon appeared, but they were not capable of explaining fully the observed ROA band signs and intensities. In this work, an analysis based both on the light scattering theory and dedicated experiments provides a more complete understanding. For example, double‐cell magnetic circular dichroism and magnetic ROA experiments with copper‐porphyrin complex show that the induced chirality is observed without any contact of the solvents with the complex. The results thus indicate that a combination of electronic circular dichroism (ECD) with the polarized Raman scattering is responsible for the effect. The degree of circularity of solvent vibrational bands is a principal molecular property participating in the event. The insight and the possibility to predict the chirality transfer promise future applications in spectroscopy, chemical analysis and polarized imaging.

We report extremely strong chirality transfer from achiral nickel complex to solvent molecules detected as Raman optical activity (ROA). Electronic energies of the complex were in resonance with the excitation-laser light. The phenomenon was observed for aw ide range of achiral and chiral solvents. Forchiral 2-butanol, the induced ROAwas even stronger than the natural one.T he observations were related to so-called quantum (molecular) plasmons that enable as trong chiral Rayleigh scattering of the resonating complex. According to am odel presented here,t he maximal induced ROAi ntensity occurs at ac ertain distance from the solute,i nathreedimensional "ring of fire", even after rotational averaging. Most experimental ROAsigns and relative intensities could be reproduced. The effect might significantly increase the potential of ROAspectroscopyinbioimaging and sensitive detection of chiral molecules.Most important molecules in living organisms are chiral and thus sensitive to circularly polarized light. This sensitivity was first explored by Pasteur, [1] and since then an amazing variety of chiroptical methods has been developed for fundamental studies and practical applications. [2] One of the youngest and most dynamically evolving tools is Raman optical activity (ROA). [3] It can provide rich stereochemical information because of the large number of vibrational bands usually exhibited by chiral molecules,a nd is directly applicable to solutions.However,the ROAeffect is weak, and alarge amount of the sample is usually needed for the analysis.T his has prompted vigorous searches for enhancement techniques, utilizing,f or example,m olecular resonance, [4] nanoplasmons (resonating metallic nanoparticles), [5] and molecular aggregation. [6] Interesting phenomena such as ROAi nduction in achiral reporter molecules in the presence of nanoplasmons or asolvent-signal enhancement under hyper-Raman scattering have been observed. [5c,7,8] Even though many properties of the nanoplasmons can be explained by established electro-magnetic and chemical theories, [9] the ROAenhancement and many chirality-transfer effects have so far resisted detailed interpretation.In this context, we believe that the strong chirality transfer under resonance conditions described in this work significantly contributes to the understanding of molecular interactions with chiral light. We report strong ROAofarange of solvents induced by achiral nickel complex under resonance conditions.C ontrary to common belief,t he chirality transfer appears quite general, and the induced ROAs ignals were even stronger than those of the Ni complex itself.F or 2butanol, ac hiral solvent, the induced ROAi ntensity was stronger than the natural one.Ther esonance-ROA phenomenon itself,a na rea of intense experimental and theoretical interest, can be rationalized only in simple cases. [4a, 10] None of them, however,i s applicable to the observations presented here.B ased on extensive experimental data and model calculations,weshow that the effect is not caused by spe...

Resonance Raman optical activity (RROA) is commonly measured as the difference in intensity of Raman scattered right and left circularly polarized light, IR−IL, when a randomly polarized light is in resonance with a chiral molecule. Strong and sometimes mono‐signate experimental RROA spectra of several chiral solutes were reported previously, although their signs and relative intensities could not be reproduced theoretically. By examining multiple light‐matter interaction events which can occur simultaneously under resonance, we show that a new form of chiral Raman spectroscopy, eCP‐Raman, a combination of electronic circular dichroism and circularly polarized Raman, prevails. By incorporating the finite‐lifetime approach for resonance, the experimental patterns of the model chiral solutes are captured theoretically by eCP‐Raman, without any RROA contribution. The results open opportunity for applications of eCP‐Raman spectroscopy and for extracting true RROA experimentally.

From the time of Louis Pasteur circular polarized light has been finding many applications in chemical analysis and spectroscopy. In their Communication on page 21895, J. Kapitán, Y. Xu, P. Bouř et al. report another modality, interference of Raman optical activity and circular dichroism, occurring during measurements of transition‐metal complexes. The chirality of the complex can be detected in the Raman scattering of the solvent; the effect is strong and may find applications in the detection of chiral compounds.

This Concept article summarizes recent work on the development of a new form of chiral Raman spectroscopy, eCP-Raman, which combines two spectroscopies: electronic circular dichroism (ECD) and circularly polarized Raman (CP-Raman). First, some puzzling observations while carrying out Raman optical activity (ROA) measurements of several transition metal complexes under resonance are described, as well as the search for the mechanisms responsible. Then an equation for quantifying the eCP-Raman contribution is presented, followed by several examples of how eCP-Raman influences the I R À I L spectra of achiral and chiral solvent molecules and of a number of chiral solutes under resonance. The conditions to extract resonance ROA, when the eCP-Raman contribution is minimized, are also discussed. Finally, we comment on the potential applications of eCP-Raman.