Structural investigation of a self-assembled monolayer material 5-[(3-methylphenyl) (phenyl) amino] isophthalic acid for organic light-emitting devices

• Molecular structure of 5-[(3-methylphenyl) (phenyl) amino] isophthalic acid was studied.
• The FT-IR, Raman, NMR and UV–vis spectra of studied molecule were compared with calculated spectra.
• The vibrational frequencies were calculated by DFT method and discussed.
• The complete assignments are performed on the basis of the potential energy distribution (PED).

The molecular structure and vibrations of 5-[(3-methylphenyl) (phenyl) amino] isophthalic acid (MePIFA) were investigated by infrared and Raman spectroscopies, UV–Vis, 1H and 13C NMR spectroscopic techniques and NBO analysis. FT-IR, FT-Raman and dispersive Raman spectra were recorded in the solid phase. 1H and 13C NMR spectra and UV–Vis spectrum were recorded in DMSO solution. HOMO–LUMO analysis and molecular electrostatic potential (MEP) analysis were performed. The theoretical calculations for the molecular structure and spectroscopies were performed with DFT (B3LYP) and 6-311G(d,p) basis set calculations using the Gaussian 09 program. After the geometry of the molecule was optimized, vibration wavenumbers and fundamental vibration wavenumbers were assigned on the basis of the potential energy distribution (PED) of the vibrational modes calculated with VEDA 4 program. The total (TDOS), partial (PDOS) density of state and overlap population density of state (OPDOS) diagrams analysis were made using GaussSum 2.2 program. The results of theoretical calculations for the spectra of the title compound were compared with the observed spectra.

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