Structural and spectroscopic studies on 2-pyranones.

Area of Science:

• Computational Chemistry
• Molecular Spectroscopy
• Organic Chemistry

Background:

• 2-pyranones are heterocyclic compounds with diverse applications.
• Understanding their electronic and structural properties is crucial for further development.

Purpose of the Study:

• To elucidate the structural and spectral characteristics of specific 2-pyranone derivatives.
• To analyze molecular properties in both ground (S(0)) and excited (S(1)) states.
• To assign UV-VIS absorption peaks and identify characteristic vibrational bands.

Main Methods:

• Experimental spectroscopy: Infrared (IR), Raman, and electronic absorption.
• Density Functional Theory (DFT) calculations: B3LYP functional with 6-31G**, 6-311++G**, and 6-31+G**5D basis sets.
• Mapping electron density isosurface with electrostatic potential (ESP) surfaces.

Main Results:

• Detailed information on molecular size, shape, charge distribution, and reactivity sites.
• Assignment of UV-VIS absorption peaks based on Time-Dependent DFT (TD-DFT) calculations.
• Identification of the first excited state as a (1)(pi,pi*) state.
• Complete vibrational analysis correlating experimental spectra with calculated frequencies and potential energy distributions.
• Characteristic vibrational bands for the 2-pyranone ring, methylsulfanyl, and carbonyl groups were identified.

Conclusions:

• The study provides a comprehensive understanding of the electronic and vibrational properties of the investigated 2-pyranone derivatives.
• The combined spectroscopic and computational approach successfully characterizes these molecules.
• The findings contribute to the knowledge base for pyranone chemistry and spectral analysis.