Use of tetraphenyl (hydroxyl) imidazole for colorimetric detection of iodide: Optical properties, computational characterizations, NBO, QTAIM, and NCI-RDG analyses

Abstract

• Optoelectronic properties of tetraphenyl (hydroxyl) imidazole were carried out. • Complexation of Imidazole with I − anion was analyzed using experimental UV spectroscopy. • Imidazole has high selectivity towards Iodide over other competitive anions. • Imidazole shows appropriate properties to constitute good I − sensors. Optical, structural, electronic, and energetic properties of tetraphenyl (hydroxyl) imidazole were carried out using B3LYP-D3/6-311G (d, p) theoretical level. Complexation of imidazole compound with Br − , Cl − , CN − , SCN − , NO 3 − , CH 3 COO − , SO 4 − and I − anions have been analyzed using experimental UV spectroscopy. Data indicated that the addition of various anion ions in imidazole solutions exhibited negligible change in the absorption spectrum. However, the intensity of the absorbance was well improved in the presence of I − . A reddish orange color was observed with the appearance of new peak at 368 nm (experimental spectra) and 337 nm (theoretical spectra). This proved that the studied imidazole has a high selectivity towards iodide over other competitive anions. Imidazole compound detected I − in the range 0–30 µM, showing good linear relationships between concentration and absorption change (R 2 = 0.93), with a detection limit of 0.73 µM. The interaction of iodide with the colorimetric chemo sensor was discussed using Natural Bond Orbital (NBO) and Quantum Theory of Atoms In Molecules (QTAIM) analyses, taking into consideration the Reduced Density Gradient (RDG) theory using 6-311G (d, p)/lanl2dz(I) method. Adsorption energy (E ad ), vibrational spectra and Frontier molecular orbitals (FMOs) were used to detect the presence of I − . Overall, the present finding exhibited that Imidazole displayed suitable properties to design good I − sensors.