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Sunday, 6 April 2014

Sucrose 2D NMR Spectra

The sugar sucrose can be used to illustrate  homonuclear 2D NMR experiment: the TOCSY.
Sucrose
Sucrose
Table sugar
Sucrose ("table sugar") is a disaccharide derived from glucose and fructose.
The interesting element from an NMR spectroscopy viewpoint is that the two monomer units are completely separate spin systems and this can be visualised in the TOCSY spectrum.
HH COSY
HH COSY
The HH COSY shows the coupling network within the molecule.
HH TOCSY
HH TOCSY
The HH TOCSY spectrum shows correlations that belong together in contiguous spin systems: in the sucrose example, this means that the protons in the respective glucose and fructose units can be assigned.
HMQC
HMQC
In the HMQC spectrum the one-bond direct HC couplings can be viewed as cross-peaks between the proton and carbon projections.
HMBC
HMBC

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