Optical Rotatory Dispersion: Its Nature and Origin

Hargreaves, M. K.

doi:10.1038/195560a0

Cited by 7 publications

(8 citation statements)

References 24 publications

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“…Wavelength dependence of chiral signal has been observed in chiroptical techniques such as absorption CD and PECD 37 , 45 . In absorption CD, it is attributed to the Cotton effect 49 , 50 , a change in the extinction coefficients of S- and R-limonene for right and left circularly polarized light 5 , 49 . In single and multi-photon PECD of limonene, varying the photon energy led to (a) modulation of the chiral signal mirroring the principal vibrational features observed in the photoelectron spectrum, and (b) flipping of the forward–backwards asymmetry in the angular emission of electrons relative to the photon beam direction 30 , 37 , 38 .…”

Section: Discussionmentioning

confidence: 99%

Chiral discrimination by recollision enhanced femtosecond laser mass spectrometry

Bégin

Alsaawy

Bhardwaj

2020

Sci Rep

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chiral molecules and their interactions are critical in a variety of chemical and biological processes. circular dichroism (cD) is the most widely used optical technique to study chirality, often performed in a solution phase. However, CD has low-efficiency on the order of 0.01-1%. therefore, there is a growing need to develop high-efficiency chiroptical techniques, especially in gas-phase, to gain background-free in-depth insight into chiral interactions. By using mass spectrometry and strongfield ionization of limonene with elliptically polarized light, we demonstrate an efficient chiral discrimination method that produces a chiral signal of one to two orders of magnitude higher than the conventional cD. the chiral response exhibits a strong dependence on wavelength in the range of 1,300-2,400 nm, where the relative abundance of the ion yields alternates between the two enantiomers. The origin of enhanced enantio-sensitivity in intense laser fields is attributed to two mechanisms that rely on the recollision dynamics in a chiral system: (1) the excited ionic state dynamics mediated either by the laser field or by the recollision process, and (2) non-dipole effects that alter the electron's trajectories. our results can serve as a benchmark for testing and developing theoretical tools involving non-dipole effects in strong-field ionization of molecules. Chiral molecules lack S n symmetry (improper rotation axis) due to the presence of a chiral center in which an atom is connected to four different groups of atoms 1. Consequently, there is a handedness to the molecule. The left-and right-handed molecules are non-superimposable mirror images of each other, called enantiomers. They have identical physical and chemical properties making it difficult to differentiate them. Chiral discrimination requires an interaction between two chiral systems-a chiral reagent with known handedness that can induce enantio-selectivity in the second chiral system. In nature, bio-molecules such as amino acids that make up life on earth are homochiral, where one enantiomer exists predominantly over the other due to asymmetric interactions 2. Homochirality plays a pivotal role in our daily life by serving as a chiral reagent for enantio-selectivity. For example, olfactory receptors in our nose, responsible for the sense of smell, interact differently with the two enantiomers of a chiral system. For instance, the right-handed enantiomer of limonene has an orange odour while the left-handed enantiomer has a lemon odour 3. In practice, enantio-selectivity can be achieved using circularly polarized light (CPL) as a chiral reagent. CD is one of the most widely used chiroptical techniques. It arises due to the coupling of the electric and magnetic dipole transitions, thereby resulting in a differential absorption of left-and right-circularly polarized light 1,4-8. CD has low-efficiency on the order of 0.01-1% because magnetic dipole transitions are involved 9-12. Moreover, CD measurements are mostly conducted in solution phase, making it diffi...

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Section: Discussionmentioning

confidence: 99%

Chiral discrimination by recollision enhanced femtosecond laser mass spectrometry

Bégin

Alsaawy

Bhardwaj

2020

Sci Rep

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“…For determining the optical rotation, Werner utilized an F. Schmidt and Haensch polarimeter [59], and originally used the d and l descriptors to describe the compounds with positive and negative rotation of 656.3 nm wavelength linearly polarized light, respectively. He subsequently reported optical rotatory dispersion (ORD) spectra which are simply plots of the variation in optical rotation of linearly polarized light with wavelength [60]. The development of the successful resolution methods is described in the doctoral thesis of Victor King [61].…”

Section: It All Began With Wernermentioning

confidence: 99%

When Stereochemistry Raised Its Ugly Head in Coordination Chemistry—An Appreciation of Howard Flack

Constable

Housecroft

2020

Chemistry

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Chiral compounds have played an important role in the development of coordination chemistry. Unlike organic chemistry, where mechanistic rules allowed the establishment of absolute configurations for numerous compounds once a single absolute determination had been made, coordination compounds are more complex. This article discusses the development of crystallographic methods and the interplay with coordination chemistry. Most importantly, the development of the Flack parameter is identified as providing a routine method for determining the absolute configuration of coordination compounds.

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“…To begin with, NCD signals result from setting a chiral structure in a handed environment created by circularly polarized light [3,16]. Photon polarization is here described by standard Stokes parameters reviewed in the Appendix [16,17].…”

Section: Orientation To Dichroic Signalsmentioning

confidence: 99%

“…The origin and nature of natural circular dichroism (NCD) were well-understood in the 1960s [3]. Chemists exploited NCD in the SHG response three decades later [4], with a surge of exploitation in studies of nanostructures and surfaces [5,6].…”

Section: Introductionmentioning

confidence: 99%

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Circular dichroism of second harmonic generation response

Lovesey

Laan

2019

Phys. Rev. B

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Polarization-dependent photon spectroscopy (dichroism) of the second-harmonic generation response is shown to reveal chiral and magnetic properties of a sample. Two dichroic signals are allowed with electric-dipole and electric-quadrupole scattering events, and both require circular polarization in the primary beam. Explicit expressions for the signals are derived using theoretical techniques from atomic physics.

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Optical Rotatory Dispersion: Its Nature and Origin

Cited by 7 publications

References 24 publications

Chiral discrimination by recollision enhanced femtosecond laser mass spectrometry

Chiral discrimination by recollision enhanced femtosecond laser mass spectrometry

When Stereochemistry Raised Its Ugly Head in Coordination Chemistry—An Appreciation of Howard Flack

Circular dichroism of second harmonic generation response

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