Tobias Schubeis

@NMRspectroscopy @nmr900 ok, thanks a lot!

@TSchubeis @nmr900 Well, if it is AB spin system you have no longer struggle with such a “big coupling”. Because it is just chem shift difference between A and B. In this case also the difference between D2O and ACN is understandable because chem shift is concentration dependent.

#NMR fam - I need your expertise. This dd, split by 327 Hz (~0.5 ppm at 600 MHz). ChatGPT tells me this must come from coupling to a spin 1/2 heteronucleus like 31P or 19F - but I do not expect anything like this in my molecule. What else can cause such a splitting? #NMRchat

@NMRspectroscopy @nmr900 I don't know the structure - I am trying to determine it. This might indeed be a AX spin system... but I don't know how this information is going to help me

@TSchubeis @nmr900 “Coupling” is really large. Even F-F coupling in diastereotopic CF2H group is around 250 Hz. Could you show me the fragment of the molecule we’re talking about? I’m pretty sure now this is diastereotopic CH2 group. And you see smth like AB spin system.

@NMRspectroscopy @nmr900 considering an integral ratio of close to 1:1 - this would mean that there are exactly two rotomers equally populated in the sample?

@nmr900 @TSchubeis What is the reason for the shape of this signal? 🤔 I mean, it is negative at some points. Maybe this large coupling is a consequence of some kind of rotamerism—for example, one induced by an amide group. In this case it is not “coupling” but doubling of your initial doublet.

@NMRspectroscopy @nmr900 The spectrum I posted was recorded in D2O, I also have data in ACN - there the splitting is even bigger: 421 Hz. There should be Sulfur in the molecule, but no Nitrogen - at least according to MS/MS

@nmr900 @TSchubeis Maybe… but I would go with changing the solvent. Rotamerism is strongly dependent on the solvent, so you might see a completely different picture.

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Today the CRMN, @cerm_cirmmp and the @osi_lv celebrated the kick-off of the @HorizonEU project Mr.LATVIA in Riga. Through expert transfers and training, @osi_lv will become a key #NMR hub and advance research across Latvia and the Baltic Sea region

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@PhunkyWitch The new Linkin park song - emptiness machine... Gets you moving!

can you guys comment a song i can add to my workout playlist?? please?

Hello #NMRchat. I have a 7 mm MAS probe which was not in use for >10 years. I tried to spin a rotor using a recent MAS3 unit and the generic spin up program - rotor didn't spin. Any advice how do I troubleshoot this? #NMR

@canklin Interesting. This comes indeed from a three membered ring. Thanks!

Hey #NMR #NMRchat. I recorded a multiplicity edited 13C-HSQC and two CH2 groups appear negative but one appears positive ... how can that happen?

@uOttawaNMR @nmr900 Thanks for the tip. If the lock is weak the sweap is noisy? Here I don't think this was the case, sample was in pure dmso-d6 and lock signal found easily

@TSchubeis Is your lock signal strong? u-of-o-nmr-facility.blogspot.com/search?q=Lock&… #nmrchat @nmr900

Hello #NMR #NMRchat fam. Anyone an idea why I get these "dirty feet" in my 1D 1H spectrum? How can I avoid that?

@LesotPhilippe You mean fill? Yes the day before

@TSchubeis Recent Helium transfer ?

@nmr900 @uOttawaNMR Interesting. It's a bruker spectrometer, standing on the ground floor but still there might be vibration... There is a lot going on in the hall. Is there an anti vibration mode on a standard bruker setup?

@TSchubeis . @uOttawaNMR The Effect of Floor Vibrations on NMR Spectra u-of-o-nmr-facility.blogspot.com/2007/09/effect… #NMRchat #NMR 🧲

@AlexGuseman In my experience they work very well with Fernbach flasks since they have a large bottom surface area... to get them off you need to gently pull the neck until they loose grip

more incubator questions....and i cant believe im asking this... but the sticky mats....Do they actually work ?

@klausenhauser Probably you can quite easily figure out if it's anion or cation... But which one? Q? Deae? S? Sp?

Found this treasure in the fridge. Suspicions as to what it could be. But how can I know for sure?

@NMRspectroscopy Additionally by adding 10% D2O there is a new peak appearing at 8.4 ppm. It could be one of those that disappeared... Or something else? Any idea?

@TSchubeis Those * are acidic protons. The only thing that comes to mind (OH, NH amine). After adding D2O they exchanged to D and disappeared.

hey #NMR #NMRchat I measured a small molecule 1H in CH3CN (red) and after adding 10% D2O to the sample (blue), there are quite some changes that I do not understand, for example: why do the three marked (*) peaks disappear? they do not seem to belong to my molecule

It makes sense, there are three OH groups in the molecule. I just didn't expect to see them... At least not as a sharp peak. Thanks fam, much appreciated!