Abstract

Quantum calculations of the physical properties (electronic and vibrational), based on density functional theory (DFT) method at B3LYP/6-31G** level of theory, were performed, by means of the Gaussian 09 set of programs, to investigate the effect of the addition of the radical CN on pyridazine molecules. The best geometry, the total energy, frontier molecular orbital energies (HOMO and HUMO), energy gap, ionization potential, electron affinity, electronegativity, chemical hardness, chemical softness, electrophilicity, dipole moment and the harmonic vibration frequencies were calculated and discussed for the study molecules. The electronic properties are computed by two different methods, a finite difference approximation and Koopman’s theorem. The study clearly shows that adding the radicals CN cause decreased the energy gap and the chemical hardness, and increase the electrophilicity. Therefore, the presence of these radicals improves the conductivities and enhances the solubility and reactivity. All the results indicate that the molecule 2,4-(CH) ₄N₂ (CN) 2 is the best option for n-type organic semiconductors.

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