Crystal Structure Based Design of Signal Enhancement Schemes for Solid-State NMR of Insensitive Half-Integer Quadrupolar Nuclei

A combination of density functional and optimal control theory has been used to generate amplitude- and phase-modulated excitation pulses tailored specifically for the (33)S nuclei in taurine, based on one of several reported crystal structures. The pulses resulted in significant signal enhancement (stemming from population transfer from the satellite transitions) without the need for any experimental optimization. This allowed an accurate determination of the (33)S NMR interaction parameters at natural abundance and at a moderate magnetic field strength (11.7 T). The (33)S NMR parameters, along with those measured from (14)N using frequency-swept pulses, were then used to assess the accuracy of various proposed crystal structures.