³⁵ Cl– ¹ H Heteronuclear correlation magic?angle spinning nuclear magnetic resonance experiments for probing pharmaceutical salts

Heteronuclear multiple-quantum coherence (HMQC) pulse sequences for establishing heteronuclear correlation in solid-state nuclear magnetic resonance (NMR) between 35Cl and 1H nuclei chloride salts under fast (60 kHz) magic-angle spinning (MAS) at high field (a Larmor frequency of 850 MHz) are investigated. Specifically, recoupling the 35Cl–1H dipolar interaction using rotary with phase inversion every rotor period or symmetry-based SR421 compared. In our implementation population transfer (PT) (D) HMQC experiment, satellite transitions saturated an off-resonance WURST sweep, a low nutation frequency, over second sideband, whereby must be same duration as time. Numerical simulations MAS D-HMQC experiment performed separately each crystallite orientation powder provide insight into dependence changes second-order quadrupolar-broadened NMR lineshape application recoupling. Two-dimensional PT-D-HMQC spectra presented amino acids glycine·HCl l-tyrosine·HCl pharmaceuticals cimetidine·HCl, amitriptyline·HCl lidocaine·HCl·H2O. Experimentally observed lineshapes compared those simulated chemical shift quadrupolar parameters calculated gauge-including projector-augmented wave (GIPAW) method: product (PQ) values exceed measured experimentally by factor 1.3 1.9.