Spin networks determination selective experiments

One-dimensional double-resonance or homonuclear spin-spin decoupling experiments can be used to furnish information about the spin network. However, we have to irradiate each proton signal sequentially and to record a larger number of ID H-NMR spectra if we wish to determine all the coupling interactions. Selective irradiation (saturation) of an individual proton signal is often difficult if there are protons with close chemical shifts. Such information, however, is readily obtainable through a single COSY experiment. 

Selective experiments enabling one to focus on a region of interest within a molecule are extremely useful becau.se of the potential for the exploitation of information present in their fine structures. Many could also be applied in a systematic manner to different spectral regions of given molecules, provided they can be acquired quickly and are suitable for automatic computer processing. Many different experimental schemes have been proposed. The DAISY experiment proposed by Friedrich etal. enables one to determine whether there are two remote spins in the same coupling network. The same authors proposed the use of. soft pulses in order to simplify three-dimensional experiments. 

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