This two-dimensional absolute-value COSY
experiment correlates protons separated by three bonds. Before setting up the
COSY experiment, see Acquiring and Processing 2D Experiments.
See the Varian Guide to NMR Experiments
for a complete description of this experiment.
To
enhance long-range 1H correlations, such as protons separated by 4
bonds, set tau=0.15 (after you have typed relayh). To de-emphasize diagonal peaks at the expense
of cross peak intensity, set p1 = 1H 60° pulse width. To RELAY the magnetization from 1H
“A” through 1H “B” to 1H “C”, set relay=1 and tau=0.06. To perform a Double-RELAY, set relay=2
and tau=0.04.
1.
Join the experiment in which the 1H reference spectrum was
collected.
2.
Type relayh.
3.
Type dg. Adjust the parameters in bold listed below for the standard
COSY:
·
sfrq=set
by spectrometer
·
tn=’H1’
·
at
= set by spectrometer
·
sw = sw from 1H reference spectrum
·
ss=2
·
tpwr = listed at console
·
pw = 1H 90° pulse width listed at console
·
p1= 1H 90° pulse width listed at console
·
d1
= 1H relaxation delay (1-2 * 1H T1)
·
d2=0
·
tof = tof from 1H reference spectrum
·
nt = multiple of 4
·
ct
= set by computer
·
dm=’n’
·
sw1 = sw from 1H reference spectrum
·
ni = multiple of 64
·
dp=’y’
·
relay=0
·
tau=0
·
fn=1024
·
fn1=1024
·
temp=30 su (to set the variable temperature unit to 30 degrees)
***TURN OFF THE SPINNER***
4.
Change ni, nt, and d1 to suit your scheduled time. Type au to start the acquisition
The
vertical (non-acquisition) resolution equals sw1/2ni.
Typical values are listed
below for sw1=4400
|
d1 |
ni |
nt |
Time |
Vertical resolution |
|
1.5 |
128 |
4 |
0:15 |
17.2 Hz |
|
1.5 |
256 |
4 |
0:31 |
8.6 Hz |
|
1.5 |
512 |
4 |
1:02 |
4.3 Hz |
|
1.5 |
128 |
16 |
1:01 |
17.2 Hz |
|
1.5 |
256 |
16 |
2:03 |
8.6 Hz |
|
1.5 |
512 |
16 |
4:09 |
4.3 Hz |
|
1.5 |
128 |
64 |
4:03 |
17.2 Hz |
|
1.5 |
256 |
64 |
8:10 |
8.6 Hz |
|
1.5 |
512 |
64 |
16:37 |
4.3 Hz |
|
2.25 |
128 |
4 |
0:21 |
17.2 Hz |
|
2.25 |
256 |
4 |
0:43 |
8.6 Hz |
|
2.25 |
512 |
4 |
1:28 |
4.3 Hz |
Processing, Displaying, and Plotting:
Process using the procedure for Processing
a 2D Absolute-Value Experiment. Plot pos.only contours. the
COSY, RELAY, and Double-RELAY spectra may be symmeterized by typing foldt.
Type acosy to perform automatic analysis of the COSY cross peaks.