The preparation and TD-DFT studies of 1-[(4-methyl-2-nitrophenyl) azo]-2-naphthalenol (C.I. Pigment Red 3) nanoparticles

Nanosized 1-[(4-methyl-2-nitrophenyl)azo]-2-naphthalenol (C.I. Pigment Red 3) particles were prepared using a facile liquid precipitation method. The morphology and electrical properties of the produced particles were characterized by SEM, ζ-potential and electrophoretic display device. The particles were ∼80 nm in size within a narrow particle size distribution and displayed excellent electrophoretic properties. The structure and geometry of 1-[(4-methyl-2-nitrophenyl)azo]-2-naphthalenol were investigated using density functional theory, for which, calculated results indicated that the compound possessed both trans- and cis- conformers. UV–vis spectroscopy of the two conformers was evaluated using time-dependent density functional theory taking bulk solvent effects into account by means of the polarizable continuum model. Vertical excitation energies and oscillator strengths were determined for the lowest-energy electronic transitions. The calculated results reproduced the experimental data and corroborated the reliability of the structural characterization of the pigment.