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Please feel free to make suggestions for future posts by emailing Glenn Facey.



Friday, July 10, 2009

31P - 13C HMQC

When most people think about HMQC or HSQC spectra they think about protons and 13C or protons and 15N. Although these are by far the most common spins to probe, the HMQC technique can be applied to other spin pairs as well. In earlier posts to this BLOG, this was demonstrated for protons and 11B and 31P and 109Ag. This post shows an application of the technique to 31P and 13C. Measurements made between spin pairs, where one of the spins is not a proton, require a triple resonance probe and the appropriate filters.
The figure below shows 31P detected 31P - 13C HMQC data for dimethyl methylphosphonate with 13C decoupling during the acquisition and 1H decoupling during the entire sequence. The spectra on the top and left-hand sides of the plots are separately run one dimensional 31P and 13C spectra, respectively, both with proton decoupling. The methyl carbon of dimethyl methylphosphonate has 1JCP = 142 Hz whereas the methoxy carbons have 2JCP = 6 Hz. Two HMQC spectra were run. The one on the left was optimized for 142 Hz and the one on the right was optimized for 6 Hz. Each spectrum shows a correlation according to its coupling constant. The data were collected on a 500 MHz instrument with the appropriate bandpass filters on each channel.

2 comments:

Sergey said...

Hello, Glenn!
I'm trying to perform the similar experiment in 1D variant on a 3-channel Bruker DRX-500 spectrometer, but it fails (very strong residual signal, no satellites). Could you kindly provide some more info about your experiment (pp used, filter&probe configuration, acquisition parameters, etc.)

Sincerely,
Sergey.

Glenn Facey said...

Sergey,

I used a Bruker 3 channel AVANCE 500 with a triple resonance X/31P/1H 5mm probe. The X channel of the probe was tuned to 13C. I used a 202 MHz bandpass filter on the 31P channel, a 125 MHz bandpass filter on the X channel and a 500 MHz bandpass filter on the 1H channel. I bought these filters from a a company called "DCI". I modified a standard Bruker HMQC pulse program to run the experiment. If you would like a copy of the program please email me at gafacey@uottawa.ca and I will forward it to you.

Good luck.

Glenn