Emerging methods for the rapid determination of enantiomeric excess

Finn, M. G.

doi:10.1002/chir.10101

Cited by 190 publications

(118 citation statements)

References 67 publications

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“…Although optically active SFG (OA-SFG) cannot distinguish left-handed molecules from right-handed ones, it can still be useful in many applications. For example, for enantiomeric excess determination 27 and for study of systems with only one enantiomer (as in most biosystems), it is often sufficient to measure the chiral strength of the sample, but not the absolute handedness.…”

Section: Comparison Of Sfg With CD and Ordmentioning

confidence: 99%

A novel spectroscopic probe for molecular chirality

Shen

2006

Chirality

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Recent advances in developing sum frequency generation (SFG) as a novel spectroscopic probe for molecular chirality are reviewed. The basic principle underlying the technique is brief ly described, in comparison with circular dichroism (CD). The significantly better sensitivity of the technique than CD is pointed out, and the reason is discussed. Bi-naphthol (BN) and amino acids are used as representatives for two different types of chiral molecules; the measured chirality in their electronic transitions can be understood by two different molecular models, respectively, that are extensions of models developed earlier for CD. Optically active or chiral SFG from vibrational transitions are weaker, but with the help of electronic-vibrational double resonance, the vibrational spectrum of a monolayer of BN has been obtained. Generally, optically active SFG is sufficiently sensitive to be employed to probe in-situ chirality of chiral monolayers and thin films. Information on molecular chirality is extremely important because it is directly related to configuration and conformation of molecules, and hence their functional properties. Techniques such as circular dichroism (CD), optical rotatory dispersion (ORD), vibrational circular dichroism (VCD), and Raman optical activity (ROA) provide chirality-specific spectroscopic information, from which both the identity and the absolute structure of chiral molecules can be obtained. 1,2 Being optical techniques, they are easily adaptable to various sample geometries and capable of remote in-situ sensing. Therefore, they have been the methods of choice for probing molecular chirality and have contributed enormously to organic chemistry, biochemistry, and pharmaceutical sciences. However, these techniques are known to rely on higher-order responses of the molecular system to the probing light. In other words, the optically active responses would vanish if the interactions involved were only electric-dipole coupling between molecules and light. They become nonvanishing through higher-order interactions, such as magnetic-dipole and electric-quadrupole couplings that are 2 -3 orders of magnitude weaker than electric-dipole coupling. As a result, the sensitivity of these techniques, as determined by the ratio of the chiral response to the achiral response (from pure electric-dipole coupling), is usually not sufficient to detect chirality of monolayers and thin films. On the other hand, the advent of new technologies, such as combinatorial chemistry 3 or the ''lab-on-a-chip,'' 4 requires rapid screening and testing of chemicals of often small quantities, sometimes down to the monolayer level.Moreover, many biological processes involve molecules that either function only when imbedded in a membrane, such as membrane proteins, or accumulate and interact mainly at interfaces. 5 A sensitive probe that allows in-situ study of molecular chirality of such systems would open up new research opportunities and provide new understanding of molecular chirality.In our laboratory, sum freq...

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Section: Comparison Of Sfg With CD and Ordmentioning

confidence: 99%

A novel spectroscopic probe for molecular chirality

Shen

2006

Chirality

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“…In Figure 1, an enantiomeric pair of rotaxanes with the specific chirality composed of a C∞v axle and a Cs ring components is shown. Rotaxanes with the specific chirality can be expected as new molecular platforms [43][44][45] for asymmetric catalysts, chiral sensors [27][28][29], etc. However, it is difficult to synthesize such rotaxanes as optically pure forms [46].…”

Section: Methodsmentioning

confidence: 99%

“…Many crops from this field of chemistry were industrialized such as ion sensors, ion selective membranes, and electrodes [4][5][6][7][8][9], which were contributed by ion recognition initiated by C. J. Pedersen and chiral selectors for chromatography [10][11][12][13][14][15] initiated by the contribution of D. J. Cram's chirality recognition technology [16,17]. Research topics such as chiral shift reagents for the determination of enantiomeric excess of chiral substance [18], besides the reagents for the determination of absolute configuration [19,20], chiral indicators [19,[21][22][23][24], and rapid chirality detection method using chiral hosts by means of mass spectrometry [25,26], as well as other well established methods [27][28][29] have long fascinated many researchers.…”

Section: Introductionmentioning

confidence: 99%

The Asymmetry is Derived from Mechanical Interlocking of Achiral Axle and Achiral Ring Components –Syntheses and Properties of Optically Pure [2]Rotaxanes–

et al. 2018

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Rotaxanes consisting of achiral axle and achiral ring components can possess supramolecular chirality due to their unique geometrical architectures. To synthesize such chiral rotaxanes, we adapted a prerotaxane method based on aminolysis of a metacyclophane type prerotaxane that had planar chirality, which is composed of an achiral stopper unit and a crown ether type ring component. The prerotaxanes were well resolved using chiral HPLC into a pair of enantiomerically pure prerotaxanes, which were transferred into corresponding chiral rotaxanes, respectively. Obtained chiral rotaxanes were revealed to have considerable enantioselectivity.

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“…To date, a number of techniques are under development for the high-throughput enantiomeric composition determination [13][14][15][16][17], including time resolved IR-thermographic method [18][19][20][21], electron spray mass spectrometry [22][23][24][25][26], capillary electrophoresis [27], UV/Vis [28][29][30], circular dichroism [31,32], and fluorescence [33,34]. Among these approaches, optical methods have been attracting increasing attention due to their ability for quick data collection and compatibility with high-throughput screening system.…”

Section: Advances In Chemistrymentioning

confidence: 99%

Chiral Recognition by Fluorescence: One Measurement for Two Parameters

Sheng

2014

Advances in Chemistry

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This outlook describes two strategies to simultaneously determine the enantiomeric composition and concentration of a chiral substrate by a single fluorescent measurement. One strategy utilizes a pseudoenantiomeric sensor pair that is composed of a 1,1 -bi-2-naphthol-based amino alcohol and a partially hydrogenated 1,1 -bi-2-naphthol-based amino alcohol. These two molecules have the opposite chiral configuration with fluorescent enhancement at two different emitting wavelengths when treated with the enantiomers of mandelic acid. Using the sum and difference of the fluorescent intensity at the two wavelengths allows simultaneous determination of both concentration and enantiomeric composition of the chiral acid. The other strategy employs a 1,1 -bi-2-naphthol-based trifluoromethyl ketone that exhibits fluorescent enhancement at two emission wavelengths upon interaction with a chiral diamine. One emission responds mostly to the concentration of the chiral diamine and the ratio of the two emissions depends on the chiral configuration of the enantiomer but independent of the concentration, allowing both the concentration and enantiomeric composition of the chiral diamine to be simultaneously determined. These strategies would significantly simplify the practical application of the enantioselective fluorescent sensors in high-throughput chiral assay.

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Emerging methods for the rapid determination of enantiomeric excess

Abstract: Methods for enantiomeric excess determination using a variety of spectroscopic techniques are summarized. Particular attention is paid to techniques that have promise for application to problems of combinatorial catalyst discovery but have not yet been so employed.

Cited by 190 publications

References 67 publications

A novel spectroscopic probe for molecular chirality

A novel spectroscopic probe for molecular chirality

The Asymmetry is Derived from Mechanical Interlocking of Achiral Axle and Achiral Ring Components –Syntheses and Properties of Optically Pure [2]Rotaxanes–

Chiral Recognition by Fluorescence: One Measurement for Two Parameters

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