RAPID ACQUISITION OF MULTIDIMENSIONAL NMR SPECTRA BY RELAXATION ENHANCEMENT ADDING PARAMAGNETIC SUBSTANCES

A method is proposed to speed-up the acquisition of multidimensional NMR experiments (nD-NMR) by addition of paramagnetic substances, which increases relaxation in the studied solute. By properly choosing the type of paramagnetic and adjusting its concentration in the sample, the PRE effect (Paramagnetic Relaxation Enhancement) is conveniently modulated, allowing a substantial reduction of experiment time of many nD-NMR, with minimum losses in sensitivity. This type of Fast-PRE-NMR methodology was optimized for 2D COSY, 2D TOCSY, 2D HMQC and 2D HMBC experiments for small and medium size-molecules and using low cost paramagnetic substances, such as Mn2+. This method allowed a reduction of the experimental time by a factor of three, providing good quality spectra and no use of artifacts. Based on these results, it is proposed a general protocol for rapid set-up of optimum paramagnetic concentration for particular solute and sample experimental conditions.