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.

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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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