The vibrational studies and theoretical investigation of structure, electronic and non-linear optical properties of Sudan III [1-{[4-(phenylazo) phenyl]azo}-2-naphthalenol]

Sudan III [1-{[4-(phenylazo) phenyl]azo}-2-naphthalenol] is non-ionic fat-soluable dye used as an additive in gasoline, oils and plastics. The molecular structure, molecular electrostatic potential, NBO analysis, linear and non-linear optical properties of Sudan III have been investigated using density functional theory (OFT) calculation with 6-311G(d,p) basis set. To investigate the tautomeric stability, optimization calculations at B3LYP/6-311G(d,p) level were performed for the azo (OH) and hydrazo (NH) forms of the title compound. The calculated first-order hyperpolarizability value is comparable with the reported values and attractive object for future studies of non-linear optics. FT-IR (4000-400 cm(-1)) and FT-Raman (3500-50 cm(-1)) spectra of Sudan III have been recorded. The vibrational frequencies determined experimentally are compared with those obtained theoretically and a vibrational assignment and analysis of the fundamental modes of the compound is performed. The scaled frequencies resulted in good agreement with the observed spectral patterns. (c) 2013 Elsevier B.V. All rights reserved.