Vibrational spectroscopy and density functional theory study of ninhydrin

Area of Science:

• Computational Chemistry
• Molecular Spectroscopy
• Organic Chemistry

Background:

• Ninhydrin is a crucial organic compound with applications in various chemical analyses.
• Understanding its molecular structure and properties is essential for optimizing its use.
• Theoretical and experimental approaches are vital for comprehensive molecular characterization.

Purpose of the Study:

• To investigate the molecular structure of ninhydrin using theoretical calculations and experimental spectroscopy.
• To predict and assign infrared (IR) and Raman spectra of ninhydrin.
• To explore the hydrogen bonding potential and electronic properties (HOMO-LUMO gap) of ninhydrin.

Main Methods:

• Density Functional Theory (DFT) calculations were employed to model ninhydrin.
• Infrared (IR) and Raman spectra were obtained experimentally.
• Fourier Transform Infrared (FTIR) spectroscopy was utilized for spectral analysis.
• B3LYP/6-311++G** level of theory was applied for computational modeling.

Main Results:

• Predicted IR and Raman spectra from DFT calculations showed good agreement with experimental data.
• All experimental FTIR and Raman bands were successfully assigned based on theoretical modeling.
• Molecular electrostatic potential surface analysis identified two hydrogen bond donors and four acceptors.
• The HOMO-LUMO energy gap was theoretically determined.

Conclusions:

• The study successfully validated theoretical predictions of ninhydrin's vibrational spectra against experimental results.
• Ninhydrin exhibits specific hydrogen bonding characteristics and electronic properties.
• The combined theoretical and experimental approach provides a robust understanding of ninhydrin's molecular structure.