A comparative study of selected disperse azo dye derivatives based on spectroscopic (FT-IR, NMR and UV–Vis) and nonlinear optical behaviors

• Vibrational spectra were examined via FT-IR and DFT calculations.
• Electronic transitions were investigated in solution environment.
• Chemical shift were determined depending on predicted and recorded NMR spectra.
• The nonlinear optical properties were addressed theoretically.

In the present work, a combined experimental and quantum chemical study on ground state equilibrium structure, spectroscopic and nonlinear optical properties of selected disperse azo dye molecules are reported. The vibrational transitions were identified based on the recorded FT-IR spectra in the range of 4000–400 cm−1 for solid state, simulated IR spectra and total energy distribution (TED) of vibrational modes. The chemical shifts were determined from the results of observed 1H and 13C NMR spectra in chloroform and dimethylsulfoxide solution. The DFT/gauge-invariant atomic orbital (GIAO) methodology was applied to predict the magnetic properties. Electronic properties were carried out by UV–Vis spectroscopy and TD-DFT/CIS approach. The nonlinear optical (NLO) features were addressed theoretically. A detailed description of spectroscopic and NLO behaviors of studied disperse azo dyes was reported with the help of comparison of experimental measurements and theoretical calculations.

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