How to obtain a good COSY spectrum of a paramagnetic compound

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How to set up the experiment in order to obtain a good COSY spectrum of Cu(II) compound?

I have tried to do it by just changing the spectrum width of both dimension, with an hour of acquistion time, but no cross peak can be observed between any signal.

Thanks

paramagnetic

asked May 21 '13 at 23:07

Kiu Chor Sham
11

How broad are the peaks in the corresponding 1D NMR spectrum? - Pascal Fricke (May 22 '13 at 02:43)

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In the canonical implementations of COSY, the cross-peaks are antiphase. In the presence of line-broadening, loss of signal intensity occurs due to the overlap of the components of the cross-peaks, which are of opposite sign in antiphase cross-peaks.

This problem may be overcome by use of modifications of the pulse sequence that produce a COSY spectrum with inphase and absorptive cross-peaks, if J/v is sufficiently large (J: coupling constant; v=line width).

A few relevant references are given below:

COSY with in-phase cross peaks. S Talluri, HA Scheraga. Journal of Magnetic Resonance 86 (1), 1-10, 1990.

Applications of COSY to paramagnetic heme-containing systems Ivano Bertini?, Francesco Capozza†, Claudio Luchinat†, Paola Turano? Journal of Magnetic Resonance. Volume 95, Issue 2, November 1991, Pages 244–252

Applications of COSY to paramagnetic heme-containing systems I Bertini, F Capozza, C Luchinat, P Turano - Journal of Magnetic …, 1991 - Elsevier

Frontiers in 2D NMR of paramagnetic metalloproteins L Banci, I Bertini, C Luchinat, L Messori… - Applied Magnetic …, 1993 - Springer

IP?COSY, a totally in?phase and sensitive COSY experiment Y Xia, G Legge, KY Jun, Y Qi, H Lee… - Magnetic Resonance in …, 2005

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answered May 25 '13 at 12:57

sekhar Talluri
621

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Asked: May 21 '13 at 23:07

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Last updated: May 25 '13 at 12:57

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