Hi Clemens,
Thanks a lot! I’ll adjust my exp parameters as you suggest and try
it again.
I found that one of the reasons I thought my COSY was “weird”
was that there seemed to be some conflicts on the assignment of the PFOA
molecule – a few papers did 1D assignments, which were my main reference
point, did not agree with other papers with assignments from COSY and NOESY.
The discrepancy seems to arise from 4J and 3J F-F couplings. Although the current
data is still not perfect but that finding makes the spectrum more reasonable.
I’ll see what I can get with the new experiments.
Thanks!
Cheers,
Paris
> From: main_at_ammrl.groups.io On Behalf Of Anklin, Clemens via groups.io
> Sent: Wednesday, July 22, 2026 9:41 PM
> To: main_at_ammrl.groups.io
> Subject: Re: [AMMRL] 19F-19F COSY Exepriments
Hi Paris
the trick with 19F COSY experiments is having a long enough evolution time
in t1 to allow the magnetization to fully evolve. with 3J F,F couplings in
the range of 10 Hz you would get maximum transfer at ca 50 msec. So the COSY
LR help in building signal intensity. The next issue is that you have a very
wide sweep width and some small couplings. You need to acquire with sufficient
resolution in f2 to somwhat adequately digitze the signals. I would set
TD in F2 to 8K or larger. and TD in F1 to 256 or 512.
This should in principle give you a decent COSY.
Clemens
On 7/22/2026 2:17 PM, Paris Ning, PhD via groups.io wrote:
Hi everyone,
I have been trying to set up a 19F COSY experiment that can be used routinely
reliably. I am using PFOA as the model molecule and we have a Bruker system.
I've tried a few pulse sequences but none gave good results:
- COSY with gradient pulse for selection and purge pulse before d1 (cosygpppqf)
- COSY with delay for longrange coupling (cosylrqf) - tried with various delay
values from 0.1 ms to 50 ms
- Vanilla COSY
Wondering if anyone has a better COSY pulse sequence or another type of cor=
relation experiments to recommend.
Thanks a bunch!
Cheers,
Paris
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Received on Wed Jul 29 2026 - 07:11:54 MST