Experimental and DFT analysis of structural and spectroscopic features of nitroterephthalic acid, and computational insights into its molecular interactions with hER-α via molecular docking

Abstract

Abstract It has become clear that the exposure to the ubiquitous xenoestrogens are the first line causatives for human breast cancer. Besides, terephthalic acid (TPA), the major chemical constituent in the synthesis of polyethylene terephthalate (PET), also shown to have carcinogenic effects. Nitroterephthalic acid (NTPA) modified PET or polyethylene glycol (PEG) polymers are suggested to have lower risk, however little known about the reactive nature of NTPA especially in terms of its interactions with estrogen receptors. Therefore, this study focuses on the investigation of structural and spectroscopic features of NTPA through experimental and theoretical methods, and the exploration of interactions with human estrogen receptor alpha (hER-α) in comparison with that of benzoic acid (BA), phthalic acid (PA), and terephthalic acid (TPA) by using molecular docking methodology. Essential quantum descriptors obtained for NTPA include electrostatic potential surface, electrophilicity and nucleophilicity from Fukui analysis, aromaticity indexes from nuclear independent chemical shift (NICS) analysis, and electronic properties like band gap and ionization potentials from population analysis. Infrared, Raman, and UV spectra are presented both experimentally and via ab initio density functional theory calculations obtained at the B3LYP 6-311++G(d,p) level of theory. Ligand-enzyme interactions were discussed within a dependency on the structural variations in four ligands in docking analysis. NTPA was found to behave like phthalic acid and highly rich in terms of conformations in monomeric and dimeric forms.