Vibrational spectroscopic [FT-IR, FT-Raman] investigation on (2,4,5-Trichlorophenoxy) Acetic acid using computational [HF and DFT] analysis

• (2,4,5-Trichlorophenoxy) Acetic acid was investigated by IR, Raman and NMR tool.
• The chemical shift of the compounds is favor for its change of chemical property.
• The Kubo gap related confirms the occurring of charge transformation between base and ligand.
• Owing to the large hyperpolarizability, the compound has binding ability.

In the present methodical study, FT-IR, FT-Raman and NMR spectra of the (2,4,5-Trichlorophenoxy) Acetic acid are recorded. The observed fundamental frequencies (IR and Raman) are assigned according to their distinctiveness region. The hybrid computational calculations are carried out by HF and DFT (B3LYP and B3PW91) methods with 6-31++G(d,p) and 6-311++G(d,p) basis sets and the corresponding results are tabulated. The impact of the presence of tri-chlorine atoms in phenyl structure of the compound is investigated. The vibrational sequence pattern of the molecule related to CH2COOH is analyzed. Moreover, 13C NMR and 1H NMR are calculated by using the gauge independent atomic orbital (GIAO) method with B3LYP methods and the 6-311++G(d,p) basis set and their spectra are simulated and the chemical shifts related to TMS are compared. A study on the electronic and optical properties; absorption wavelengths, excitation energy, dipole moment and frontier molecular orbital energies, are performed by HF and DFT methods. The Kubo gap of the present compound is calculated related to HOMO and LUMO energies which confirm the occurring of charge transformation between the base and ligand group. Besides frontier molecular orbitals (FMO), molecular electrostatic potential (MEP) was performed. NLO properties related to Polarizability and hyperpolarizability are also discussed.

The diagram shows that, the contour map with positive and negative iso values and it is limited at ±0.02. Molecular electrostatic potential view is mapped up at the level of B3LYP/6-311 + G(d,p) theory with optimized geometry. The color code of these maps is in the range between −4.26 a.u. (deepest red) to 4.26 a.u. (deepest blue) in compound. The positive (blue) regions of MEP are related to electrophilic reactivity and the negative (green) regions to nucleophilic reactivity. In the MEP map of the present compound, the negative regions are mainly localized on COOH group. A maximum positive region is localized on the CH2 groups indicating a possible site for nucleophilic attack. Though, the molecule contains three Cl atoms with benzene ring, the positive and negative potential regions located with the CH2COOH group. From these results, it is inferred that, when the compound docked with protein structure, the CH2COOH group in the molecule act as main root to bind.Figure optionsDownload as PowerPoint slide