Synthesis , Characterization , and study of the Spectral and Electronic Properties of a New Azo Dyes Compounds

Abstract

In this study two new azo dyes were prepared from 4-acetaminophenol with 4-amino-N-2-pyrimidinylbenzenesulfonamide
& 4-amino-N-(5-methyl-3-isoxazolyl)-benzenesulfonamide were prepared. The prepared
by Fox method, the azo dyes were identified by IR- spectrophotometer, UV-visible spectroscopy and
elemental analysis (CHN). The absorption spectra of the azo dye was recorded with wavelength in the range
(360-600) nm in universal buffer solution of different pH values. From these spectra, the ionization and
protonation constant were calculated by using the half height method. It found that the value of the ionization
constant (pKa) closely which interpret the ionization of the hydroxyl group. Theoretical calculations for azo
dyes were studied by quantum chemical calculations. The optimized structures of the azo dyes were obtained
by molecular mechanics (MM+), and then further geometry optimization was carried out by the semiempirical
molecular orbital theory at the level of AM1 of the theory. Study Shown, the configuration II more
stable because of have high energy gap ΔE and high stability. Also the dipole moment, heats of formation,
molecular orbitals energy of HOMO and LUMO were calculated.