Vibrational Spectroscopy and Computational Studies of Cubane-1,4-Dicarboxylic Acid

Area of Science:

• Solid-state chemistry
• Molecular spectroscopy
• Computational chemistry

Background:

• Cubane-1,4-dicarboxylic acid is a precursor to cubane.
• Its vibrational properties and crystal dynamics are under-explored.

Purpose of the Study:

• To comprehensively characterize cubane-1,4-dicarboxylic acid's vibrational spectra.
• To investigate the influence of deuterium substitution on its dynamics.
• To elucidate the role of crystal structure and conformers in its vibrational behavior.

Main Methods:

• Infrared (IR) spectroscopy
• Raman spectroscopy
• Inelastic neutron scattering (INS)
• Density Functional Theory (DFT) calculations

Main Results:

• Vibrational spectra of cubane-1,4-dicarboxylic acid and its deuterated isotopomer were obtained.
• DFT calculations revealed largely independent dynamics between the carboxylic acid groups and the cubane core.
• The observed spectral changes upon deuteration are primarily attributed to increased substituent mass.
• Distinct C-O-H bending mode energies were identified for the syn and anti conformers present in the crystal structure.

Conclusions:

• The vibrational dynamics of cubane-1,4-dicarboxylic acid are mainly governed by substituent mass rather than strong coupling with the cubane core.
• The presence of syn and anti conformers influences specific vibrational modes, particularly C-O-H bending.
• This study provides a detailed understanding of the vibrational properties of a key cubane precursor.