Conformational and vibrational reassessment of solid paracetamol

Area of Science:

• Solid-state chemistry
• Computational chemistry
• Spectroscopy

Background:

• Paracetamol is a widely used analgesic and antipyretic.
• Accurate knowledge of its vibrational spectrum is crucial for quality control and research.
• Existing literature contains potential misassignments of vibrational modes.

Purpose of the Study:

• To provide a detailed and accurate understanding of paracetamol's vibrational spectrum.
• To reassign vibrational modes, especially those involving hydrogen bonds.
• To correct erroneous data in the existing literature.

Main Methods:

• Comprehensive spectroscopic analysis including infrared, Raman, and inelastic neutron scattering (INS).
• Computational approach incorporating intermolecular interactions in the solid state.
• Reassessment and correction of vibrational assignments for paracetamol.

Main Results:

• A full reassessment of paracetamol's vibrational assignments was performed.
• Incorrect data analysis and misassignments from previous studies were identified and prevented.
• Vibrational modes of hydrogen-bonded NH and OH groups were correctly reallocated to bands shifted up to 300 cm^-1.

Conclusions:

• This work establishes accurate vibrational assignments for paracetamol.
• The findings contribute to a more reliable understanding of paracetamol's solid-state properties.
• Corrected data prevents the propagation of errors in future research and analysis.