One of my compound gave me all 1H peaks in aliphatic region very broad and no splitting.Aromatic peaks are well split.Shimming is very good.solvent used is CDCl3.Same is the case with APT.Very poor broad Carbon peaks in aliphatic region with sharp aromatic carbons.
COSY,NOESY and HSQC also similar.Can someone suggest a possible reason for it .And methods to overcome it.Compound is pure.It has an amide structure.OCH3 in 1H gave broad but in carbon gave a sharp peak.
will be thankfull if you can e mail me to [email protected]
I have bruker 500MHz NMR room temperature BBFO probe
Thanks
It sounds like you have a dynamic exchange going on between two (or more) conformers/rotamers of your compound. Can you try and raise the temperature a bit? Even just 10 degrees might be enough (though that depends ...). Or else change the solvent; solvent can affect conformational equilibria, too.
I have also observed long chains exhibiting differential tumbling behaviour in DMSO so that the aromatic portion of the molecule moves quickly but the end of the chain moves slowly causing different line widths. Stan's cure will also handle this - warm it or put it into a less viscous (or less anisotropic) solvent...
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