Info For Group Members
Recording of HMQC-spectra on the Bruker 500-2
(Please refer also to the Bruker manual)
- Calibrate the 90 deg pulse for 1H
and 13C
- Determine T1 for 1H
- rpar HMQC.BBI
- eda: set SW to the smallest window possible. F2 channel
for 1H NMR window, F1 channel for 13C NMR
window. Use default AQ value in the parameter file. Set O1P value as 1H
O1P, O2P value as 13C O1P. Set TD for F2 channel as 1 k, TD for F1
channel as 256.
- set P1 and D1 to 1.25xT1 as determined for 1H
NMR, set P3 to 13C NMR P1 value. Double check the power
level, i.e. PL1= 0, PL2= -3.
- choose NS in multiples of 4, and Dummy Scan DS as
16.
- Optimize D7: Set starting value of d7 = 400msec. Enter acqu
to enter acquisition window, enter gs to start go setup
routine. Adjust the value of d7 to reach the minimum
internsity. Set d7 as that value and type STOP and
click the RETURN button.
- Enter rga to optimize the receiver gain.
- check the required experiment time with expt. If the time
is too long, either reduce NS or the number of experiments in F1 (eda -
TD(F1)=128-512)
- Start experiment: ZG. The spectrum accumulated so far can
be viewed any time by xfb.
Phasing:
- xfb (can be entered anytime during spectrum acquisition to
check the spectrum achieved so far, but MUST be entered at the end of
data acquisition. Each experiment increases the resolution in F1.
Comparable to tr in 1D.)
- The standard setting is to display a magnitude spectrum and
phasing is neither required nor possible.
- To display a phase sensitive spectrum, type edp and change phase
correction from mc to pk for F2 and F1. Enter RSER 1, then SINM,
then FT, you should see a normal 1D 1H NMR
spectrum. Manually phase the spectrum as you would any 1D spectrum
EXCEPT that when you are finished, click “RETURN” and select “Save as
2D & return”. Then click the “2D” button to return to 2D spectrum.
Enter xau calcphinv to determine phase correction in F1, then xfb
again. At this point, the spectrum should be correctly phased.
Plotting:
- rpar standard2d: Load only the plot parameters (clicking
on plot)
- edg: Adjust the values as needed, refer also to the bruker
manual.
- Zoom the desired region, click on Def-Plot, plot.
13C coupled HMQC
- eda: Change pulse sequence to invbtp.hein. This is
the standard HMQC pulse sequence, only that decoupling on 13C
is turned off during data acquisition.
- record and phase spectrum like normal HMQC.
- Remember: Since acquisition takes place on 1H, the
HMQC spectrum contains all homonuclear H-H coupling. Determination of
coupling constants is thus only advisable, if the 1H
resonance appears as a singlet.
