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Binuclear spin state selective detection of $^1H$ single quantum transitions using triple quantum coherence: A novel method for enantiomeric discrimination

Baishya, Bikash and Prabhu, Uday Ramesh and Suryaprakash, N (2008) Binuclear spin state selective detection of $^1H$ single quantum transitions using triple quantum coherence: A novel method for enantiomeric discrimination. In: Journal of Magnetic Resonance . (In Press)

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Abstract

In the present work a novel methodology is developed for the unambiguous discrimination of enantiomers aligned in chiral liquid crystalline media and the simultaneous determination of $^1H-^1H$ and $^{13}C-^1H$ couplings in a single experiment. An INEPT transfer and back transfer of magnetization to protons retain the $^{13}C$ edited $^1H$ magnetization which is utilized to generate spin selective homonuclear triple quantum coherence of dipolar coupled methyl protons. Spin selective correlation of triple quantum to single quantum coherence results in spin state selective detection by $^{13}C$ spin and the remaining passive protons. The difference between the successive transitions in the triple quantum dimension pertains to sum of the passive couplings and results in enhanced resolution by a factor of three. This results in unambiguous chiral visualization. The masked $^{13}C$ satellite transitions in the single quantum spectrum are extracted for chiral discrimination. The technique retains all the passive homo- and heteronuclear couplings in the triple quantum dimension by the application of non-selective refocusing pulse on $^1H$ as well as on $^{13}C$ spins. This, however, refocuses the chemical shift evolution in the triple quantum dimension, and also overcomes the problem of field inhomogeneity. The method enables the determination of spectral information which is otherwise not possible to derive from the broad and featureless proton spectra. The elegant experimental technique has been demonstrated on different chiral molecules.

Item Type: Journal Article
Additional Information: Copyright of this article belongs to Elsevier Inc. The article is in press and the remaining publication details are awaited.
Keywords: Triple quantum NMR;Enantiomer discrimination;Chiral liquid crystal;Spectral analyses;Spin state selection;Residual dipolar couplings
Department/Centre: Division of Chemical Sciences > Solid State & Structural Chemistry Unit
Date Deposited: 27 Mar 2008
Last Modified: 19 Sep 2010 04:43
URI: http://eprints.iisc.ernet.in/id/eprint/13520

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