[Study on structure, charge and spectrum for para-halogenated diphenyl ethers through density functional theory]

Area of Science:

• Computational Chemistry
• Molecular Spectroscopy
• Environmental Chemistry

Context:

• Diphenyl ether and its halogenated analogs are important industrial chemicals.
• Understanding their molecular properties is crucial for predicting environmental behavior and reactivity.
• Previous studies have not fully elucidated the relationship between halogen substitution and vibrational spectra.

Purpose:

• To investigate the molecular geometry, charge distribution, and vibrational spectra of diphenyl ether and three para-halogenated derivatives using DFT.
• To assign the infrared and Raman spectrum vibrations for these compounds.
• To analyze the effect of para-halogen substituents on charge distribution and vibrational mechanisms.

Summary:

• Calculations at the B3LYP/6-31(d) level determined optimal molecular geometries and predicted infrared/Raman spectra.
• Analysis of charge distribution revealed significant effects of halogen substituents, particularly on the para-carbon.
• The study innovatively links charge distribution to the vibration mechanism and rules of characteristic vibrations.

Impact:

• Established a correlation between halogen electronegativity, atomic radius, C-X bond length, and environmental degradability.
• Demonstrated that increased halogen electronegativity leads to larger charge gaps and higher vibration frequencies.
• Provides fundamental insights into the structure-property relationships of halogenated diphenyl ethers for chemical design and environmental risk assessment.