Simplifying the Complex $^1H$ NMR Spectra of FluorineSubstituted Benzamides by SpinSystem Filtering and Spin-State Selection: Multiple-Quantum-Single-Quantum Correlation

Baishya, Bikash and Reddy, Manjunatha GN and Prabhu, Uday Ramesh and Row, Guru TN and Suryaprakash, N (2008) Simplifying the Complex $^1H$ NMR Spectra of FluorineSubstituted Benzamides by SpinSystem Filtering and Spin-State Selection: Multiple-Quantum-Single-Quantum Correlation. In: The Journal of Physical Chemistry A, 112 (42). pp. 10526-10532.

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Abstract

The proton NMR spectra of fluorine-substituted benzamides are very complex (Figure 1) due to severe overlaP of ${^1}H$ resonances from the two aromatic rings, in addition to several short and long-range scalar couplingS experienced by each proton. With no detectable scalar couplings between the inter-ring spins, the ${^1}H$ NMR spectra can be construed as an overlap of spectra from two independent phenyl rings. In the present study we demonstrate that it is possible to separate the individual spectrum for each aromatic ring by spin system filtering employing the multiple-quantum-single-quantum correlation methodology. Furthermore, the two spin states of fluorine are utilized to simplify the spectrum corresponding to each phenyl ring by the spinstate selection. The demonstrated technique reduces spectral complexity by a factor of 4, in addition to permitting the determination of long-range couplings of less than 0.2 Hz and the relative signs of heteronuclear couplings. The technique also aids the judicious choice of the spin-selective double-quantum-Single-quantum J-resolved experiment to determine the long-range homonuclear couplings of smaller magnitudes. filtering employing the multiple-quantum-single-quantum correlation methodology. Furthermore, the two spin states of fluorine are utilized to simplify the spectrum corresponding to each phenyl ring by the spinstate selection. The demonstrated technique reduces spectral complexity by a factor of 4, in addition to permitting the determination of long-range couplings of less than 0.2 Hz and the relative signs of heteronuclear couplings. The technique also aids the judicious choice of the spin-selective double-quantum-single-quantum J-resolved experiment to determine the long-range homonuclear couplings of smaller magnitudes.

Item Type:	Journal Article
Publication:	The Journal of Physical Chemistry A
Publisher:	American Chemical Society
Additional Information:	Copyright of this article belongs to American Chemical Society.
Department/Centre:	Division of Chemical Sciences > Solid State & Structural Chemistry Unit Division of Chemical Sciences > NMR Research Centre (Formerly Sophisticated Instruments Facility)
Date Deposited:	25 Nov 2008 10:26
Last Modified:	19 Sep 2010 04:52
URI:	http://eprints.iisc.ac.in/id/eprint/16517

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