So I'm trying to get a 15N CIGAR param set up on our Avance II 500Mhz with
a new Prodigy cryoprobe system. In short, the performance of the
experiment as I've set it up is VERY poor compared to just using the
*15N-HMBC*.
Beginning from the 15N-HMBC I've loaded the '*hmbcacbigpl2ndaqf*' pulse
sequence. I think this doing 2 low pass filters to suppress 1 bond
coupling. (I would actually prefer NOT to do this but there does not seem
to be a CIGAR sequence available which does not include it.)
I've loaded most of the parameters as described in the probe file and tried
to figure out the rest from my limited knowledge of this experiment and
what these params mean.
So here are the ones I'm unsure about and I think they may contain the
issues...
cnst2 J(XH) - no idea what I need to put here. I assume this is a 1 bond
coupling value?
cnst6 J(XH) min - min 1 bond coupling? maybe 60hz?
cnst7 J(XH) max - max 1 bond coupling? maybe 90hz?
cnst14 J(XH) long range min - 3 hz?
cnst15 J(XH) long range max - 10 hz?
cnst16 J(scale) factor - I have no idea what this should be. I've dug up
that setting it to one essentially does not use it I think?
As per the pulse program I'm a shape pulse Crp60,0.5,20.1 which I think is
the standard CHIRP pulse. I've set J14 (the length of this shaped pulse)
to 500us.
There are a bunch of gradients which I'm just using the pulse program
values - but I don't know if they need to be altered for 15N. The first 3
Gpz1-3 I've left as they came from the 15N-HMBC (70:30:50.1)
Anyway I'm looking for basic/standard parameters for organics...
alkaloids, Nitrogen heterocycle, peptides... a generic experiment to make
available in ICON-NMR.
Anyone have experience with this and/or a filled in parameter set...
Thanks!!
--
Ken Knott
Department of Chemistry
Analytical Services
Virginia Tech
(540)267-6502 (Cell)
(540)231-0885 (Office)
Received on Wed Oct 28 2015 - 09:43:01 MST