Synthesis, spectral, SHG efficiency and computational studies of some newly synthesized unsymmetrical azines of 4-biphenylcarboxaldehyde

• A series of novel unsymmetrical azines 2–8 were synthesized and analyzed by some spectral studies.
• Hyperpolarizability, dipole moment, HOMO–LUMO energies were computed.
• Computed IR frequencies are compared with the observed values.

A series of novel unsymmetrical azines 2–8 are prepared and characterized by FT-IR, 1H, 13C NMR, Mass and UV spectral studies. The Gaussian-03 B3LYP/6-311+G(d,p) calculations on these azines are used to evaluate the heat of formation of the different conformers, identify the stable conformation, to determine dipole moment (μ), polarizability (α0), first hyperpolarizability (βtot), selected geometrical parameters, MEP surface, frontier molecular orbital energies (HOMO–LUMO) and their energy gap. The μ, α0, βtot values clearly depict that the unsymmetrical azine 8 is found to have a good NLO property compared to other azines 1–7. The SHG measurement of unsymmetrical azine 8 was performed by Kurtz and Perry powder method and the results indicated that the azine 8 is having comparable efficiency as that of potassium dihydrogen phosphate (KDP) crystal. The natural bond orbital (NBO) analysis of the unsymmetrical azines 2–8 are also made using B3LYP/6-31G(d,p) basis set.

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