Relaxation delay shielding

Since the short relaxation times associated with a quadrupolar nucleus drastically reduce the time delay to be applied in an NMR experiment between two pulses, measuring times are short or, in other words, distinct NMR signals can often be detected with a limited time spent down to micromolar concentrations. Along with this apparent advantage, quadrupolar nuclei provide information in addition to the classical parameters chemical shift (or shielding) and nuclear spin-spin coupling constants. Variations in linewidths for quadrupolar nuclei are another sensitive quantity allowing for the evaluation of the electronic and the steric situation in the first coordination sphere of a vanadium compound, its periphery, its (local) symmetry and its interaction with the matrix, i.e. counter-ions, solvent molecules and other constituents present in solution. 

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