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Tuesday, July 28, 2009

13C NMR with 1H and 31P Decoupling

NMR users are very familiar with the advantages of proton decoupling when observing 13C. The 13C NMR spectra of phosphorus containing compounds can be made simpler by applying 31P decoupling either on its own or in addition to proton decoupling. The figure below shows the 13C NMR spectrum of dimethyl methylphosphonate with all possible combinations of proton and 31P decoupling. The data collection required a triple resonance probe with the appropriate band pass filters.

3 comments:

Anonymous said...

Hi Glenn,

how did you manage to run a 13C NMR experiment with both, 1H and 31P decoupling? Which pulse programe and which decouple technique did you use?

Cheers
Kai

Glenn Facey said...

Hi Kai,
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 zgpg pulse program to incorporate inverse gated decoupling from the F3 channel. (be below)

Glenn

;avance-version (07/04/03)
;1D sequence with power-gated decoupling for f2 channel
;inverse gated decoupling for f3 channel
;using 30 degree flip angle
;
;$CLASS=HighRes
;$DIM=1D
;$TYPE=
;$SUBTYPE=
;$COMMENT=


#include
#include


"d11=30m"


"DELTA=d1-30m"


"acqt0=-p1*0.66/3.1416"


1 ze
d11 pl12:f2 pl16:f3
2 30m do:f2
10u pl13:f2
d11 cpd2:f2
DELTA
4u do:f2
10u pl12:f2
30m cpd2:f2 cpd3:f3
p1*0.33 ph1
go=2 ph31
30m do:f2 do:f3 mc #0 to 2 F0(zd)
exit


ph1=0 2 2 0 1 3 3 1
ph31=0 2 2 0 1 3 3 1

Kai said...

Hi Glenn,

after I received the correct low-pass filter (13C pass; 31P stop), the experiment works very well!
Thanks for you help!

Cheers
Kai