Dissymmetries in fluorescence excitation and emission from single chiral molecules

Abstract

Chirality in molecular systems plays profoundly important roles in chemistry and physics. Most chemistry students are introduced to the concept of chirality through demonstrations of the interaction of chiral molecules with polarized light manifested as an ''optical rotation'' leading to the ''(1)'' and ''(2)'' [or dextrorotatory (d-) and levorotatory (l-)] designations of chiral compounds, with the subsequent determination of absolute stereochemical configuration by chemical or physical means enabling application of the familiar ''R'' and ''S'' labels. Although the intrinsic molecular parameters that control the dissymmetric light-matter interaction in chiral systems are well understood, we have only recently begun to ask questions regarding the role of local molecular environment and hidden heterogeneities associated with the ensembleaveraged molecular chiroptical response. In this mini-review, we discuss some of our recent research on application of single-molecule spectroscopy as a tool for probing heterogeneities and fluctuations of chiroptical dissymmetries in condensed phase.

Disentangling the role of linear transition dipole in band-edge emission from single CdSe/ZnS quantum dots: Combined linear anisotropy and defocused emission pattern imaging

“…16 In defocused imaging, the contribution of this third dipole component to DEPs is subtle. 9 Likewise, Bohmer and Enderlein have developed a parameterized model to account for ellipticity and third dipole components. 9 Likewise, Bohmer and Enderlein have developed a parameterized model to account for ellipticity and third dipole components.…”

Circular Polarization of Luminescence as a Tool To Study Molecular Dynamical Processes

“…Such spatial separation is possible with e. g. a Wollaston prism or a Rochon prism and has recently been applied. [31] The spatial separation of the circular polarizations makes the most efficient use of emitted photons and eliminates the time restrictions on the readout of the detector. Spatial separation is thus fully compatible with e. g. a CCD camera.…”

“…[190][191][192][193] Hence degrees of circular polarization from immobile molecules differ considerably from the results in solution. [194] In fact it has been realized early on that anisotropy can play a role in CPL measurements especially under where photoselection in excitation occurs and where tumbling is slow. [195] Finally, as we have discussed earlier, even achiral molecules may emit circularly polarized photons in specific direction.…”

Fluorescence Spectroscopy of Enantiomeric Amide Compounds Enforced by Chiral Light

“…Being a fluorescence-based characterization, FDCD was expected to offer higher sensitivity and specificity of chiral detection. It was previously applied in the detection of structural change in the tertiary structure of metmyoglobin [13], as well as in exciton-coupled stereochemical analysis [14,15], and it was proposed for measurements of the enantiomeric excess in substances containing randomly orientated absorbing molecules [16]; moreover, FDCD was used in attempts to detect single-molecule chirality [17][18][19]. Another application of FDCD was to study the CD of chiral Eu(III) complexes, where conventional CD would require high concentrations and high material volume [20].…”