Coupled spin systems atomic sequence

The advantages of the TOCSY experiment have led to the implementation of spinlock sequences in heteronuclear correlation experiments to detect additional homonuclear coupling interaction. In the l C, IR TOCSY-HMQC experiment in addition to cross peaks from one-bond connectivities between a DC and a IR nucleus there are correlation peaks to protons which are coupled to the primary proton by homonuclear H, H coupling. The advantage of this method is that it allows the differentiate between overlapped iR signals of different spin systems provided that the spin systems differ by the carbon shift of at least one carbon atom. This approach is shown by the simulations in the Check it 5.4.2.4. 

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