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Is it possible to obtain this experiment with a BBI 400 MHz probe? All the tries I have made they have been unsuccessful

asked Jun 23 '14 at 00:47

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Gohuma1
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INADEQUATE experiment is quite problematic. Firstly you need to calibrate 90 degree carbon pulse (it's not that easy as in case of proton). If I recall correctly BBI 400 MHZ probe is designated for 5 mm tubes. 10 mm would be better choice for INADEQUATE. Concentration of compound is crucial for this kind of experiment. If you want to obtain this spectrum in reasonable time, concentration should be at level that will allow you to obtain one dimensional 13C spectra with signal to noise ratio value about 20 (from one scan !). (Propability to find 13C-13C bond is about 0,0121% ) Try to run ADEQUATE experiment. Unfortunately avaible only for carbons directly connected with protons.

Try to run this experiment for some small molecule with different types of carbon atoms. For example menthol is quite useful for it (it has great solubility in CDCl3). Concetration of 100 mg/ml should be ok. Please tell me your values of parameters TD1, AQ, NS, DS, SW, O1P.

Good luck Arkadiusz Leniak

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answered Jun 23 '14 at 03:17

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Arkadiusz Leniak
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updated Jun 23 '14 at 04:52

I have never performed a ADEQUATE experiment. What is the pulse program? Could you give me more information? I would appreciate it because I do not have to much experience in NMR and training. - Gohuma1 (Jun 25 '14 at 04:15)

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Hello, Arkadiusz is absolutly right!

BBI is an inverse probe, for detecting the very sensitive protons 1H - normally as 5 mm or 3 mm versions!

BBO is the direct probe, detecting the hetero nucleus most sensitive (inner coil, decoupling with the outer coil the protons). These you can get in 5 and 10 mm version.

There you can detect better the hetero nucleus 13C with HETCOR, COLOC or INADEQUATE. COSY/ROSY/TOCSY/NOESY as well HMBC, HMQC and HSQC and other derivatives are pretty well measured with an inverse probe - you are detecting your Carbon as a Proton => inversely!

Or you use a OneNMR / royal / ???? probe where the inner coil/outer coil limits are vanished.

Rise your concentration - use a Shigemi tube system, there only the NMR sensitive window of the coil is filled with the solvated substance, the rest is a special susceptiblity matched glass material!

Yours sincerely,

Uli

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answered Jun 23 '14 at 06:00

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Ulrich Haunz
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I have a BRUKER 5mm PABBI 1H/D-BB Z-GRD probe. TOPSPIN 1.3.

I have started this esperiments with lysine in D2O (500mg in 0.8 ml D2O, all completelly solved). I see perfectly the 13C APT even in only one scan.

The parameters for the INADEQUATE are:

SW2=180, SW1=360

OP1P=90

O2P=5

TD0=1

AQ_MOD=DQD

FnMODE=QF

NS=128

FIDRES1=141.5Hz FIDRES2=17.7Hz

DS=16

CNST3=40

D1=5

Thank you, for your cooperation.

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answered Jun 24 '14 at 04:33

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Gohuma1
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Hmmm all these parameters looks fine to me. CNST3 is value of J(C,C) ? Which pulse program did you use, and what do you mean by "unsuccessful" experimets ? No signals at all ? Only noise ? Try to set CNST3 at 33 ( according to this paper http://pubs.acs.org/doi/abs/10.1021/ja00838a065). - Arkadiusz Leniak (Jun 24 '14 at 22:14)

Yes, CNST3 is de J(C,C), 40 Hz I only see some weak signals but without any correlation. I will try with 33 Hz. May the but lock that I have due to the poor concentration of D2O in relationship with the lysine affect the analysis? - Gohuma1 (Jun 25 '14 at 04:18)

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Lock shouldn't be a problem. For example in case of peptides or nucleic acids one doesn't want to change hydrogen bonds within molecule (deuterium is similar but also different than proton) When one changes, even a little, 300 hydrogen bonds in single molecule conformation will change and probably signals will shift). To make measurments and not change the molecule by deutered solvent, one uses D2O/H2O (0,1:0,9 ml:ml). That kind of solvent allows to lock sample but it needs higher lock power.

You said that you had 500 mg in 0.8 ml. I think that the real problem is concetration of lysine. It's not behaving like solution, but probably it's closer to gel or solid. In solution Brown thermical moves allows to average dipol influence of neighbouring molecules. But if you have solid (molecules packed in spatial order) or very concetrated solution or gel this dipol interactions will speed up relaxation (signals will be broad). In NMR of solids you can rotate it with magic angle, but in solution it will not be possible.

Can you tell me 1/2 width (command hwcal) of few peaks on 1H spectrum ? If they are broad (and probably they are) try to run 1H in higher temperature (for example 60 degrees) and compare 1/2 width of coresponding peaks. Higher temperature will have two results - lower viscosity of solvent and faster thermical moves of molecules in solvent. Or just try to run INADEQUATE with lower concetration of Lysine. I suppose that 300mg/0,5 ml should make the deal.

Ah and one more thing, you posted some of aqusition's parameters, but you didn't give TD1. Maybe there you have some wrong parameters in proccessing section ?

I would be glad if you could send me full data set (1H and that unsuccesful INADEQUATE), I could take a look at it. my mail : aleniak@icho.edu.pl

Best regards and good luck Arkadiusz

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answered Jun 26 '14 at 19:35

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Arkadiusz Leniak
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Asked: Jun 23 '14 at 00:47

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