Synthesis, structural and computational characterization of 2-amino-3,5-diiodobenzoic acid and 2-amino-3,5-dibromobenzoic acid

• The titled compounds were studied with XRD, FT-IR and UV–Vis methods.
• Molecular geometries and all possible positional isomers were determined using DFT.
• NLO calculations reveal the nonlinear optical material characters of the compounds.
• Electrophilic attack regions were determined by MEP maps and Fukui functions.
• Natural atomic charges of the compounds were determined by NPA method.

The benzoic acid compounds 2-amino-3,5-dibromobenzoic acid (2A35Br) and 2-amino-3,5-diiodobenzoic (2A35I) acid have been synthesized and characterized by single-crystal X-ray diffraction, FT-IR spectroscopy, UV–Vis spectroscopy and computational methods. Molecular geometry, intra- and inter-molecular interactions have been investigated by using X-ray diffraction technique. Fundamental vibrational bands of the title compounds were founded by FT-IR and UV–Vis method was used to obtain electronic bands. Geometry optimizations and the calculation of IR frequencies were performed both Gaussian type orbitals at Gaussian 09W and Slater type orbitals at ADF2009.01 software. The calculations are compatible with the experiment results. In addition, geometrical parameters, energies, HOMO–LUMO gaps and electrophilicity indexes have been calculated for thirty possible positional isomers of 2A35Br and 2A35I. Calculations show that 2A35Br and 2A35I isomers have the lowest energy, the narrowest HOMO–LUMO gap and the highest electrophilicity index values. Molecular electrostatic potential maps, Fukui indices, natural bond orbital analysis, thermodynamic parameters and non-linear optical properties of the 2A35Br and 2A35I were also investigated by theoretical calculations.

Molecular electrostatic potential maps of 2A35Br (left) and 2A35I (right).Figure optionsDownload as PowerPoint slide