Polymorphism in Sulfanilamide: ¹⁴N Nuclear Quadrupole Resonance Study.

Area of Science:

• Solid-state chemistry
• Materials science
• Analytical chemistry

Background:

• Polymorphism significantly impacts drug properties and efficacy.
• Characterizing different crystalline forms is crucial in pharmaceutical development.
• Nuclear Quadrupole Resonance (NQR) spectroscopy offers a sensitive probe for molecular environments.

Purpose of the Study:

• To showcase the chemical and pharmaceutical selectivity of 14N NQR spectroscopy.
• To investigate the polymorphism of sulfanilamide using 14N NQR.
• To establish NQR as a tool for polymorph identification and characterization.

Main Methods:

• Studied three known polymorphs of sulfanilamide.
• Utilized 14N NQR spectroscopy to analyze the crystal structures.
• Measured temperature dependence of quadrupole frequencies (ν+, ν-) and spin-lattice relaxation times (T1).

Main Results:

• Identified two distinct nitrogen sites within the crystal structure for each sulfanilamide polymorph.
• Observed two sets of three 14N NQR transition frequencies at room temperature.
• Demonstrated that a single NQR frequency is sufficient for polymorph characterization.
• Measured transition temperatures between polymorphs and estimated post-treatment ratios.

Conclusions:

• 14N NQR spectroscopy provides a selective and efficient method for distinguishing sulfanilamide polymorphs.
• The study validates the application of NQR in pharmaceutical solid-state analysis.
• NQR parameters offer unique fingerprints for crystalline material identification.