Experimental and density functional studies on 4-(4-cyanobenzylideneamino)antipyrine

Abstract

4-(4-cyanobenzylideneamino)antipyrine (CBAP) has been synthesized and characterized by elemental analysis, FT-IR, UV-VIS and X-ray single crystal diffraction techniques. Crystallographic study reveals that the compound adopts trans configuration about the Schiff base imine double bond. The substituted p-cyanophenyl ring indirectly linked to the pyrazoline ring by the C=N double bond is almost coplanar with the pyrazole ring, whereas the phenyl ring directly attached to the pyrazoline ring forms an effective dihedral angle. Density functional calculations have been carried out to optimize and to characterize the title compound by using B3LYP method at 6-31G(d) basis set. The calculated results show that the optimized geometry can well reproduce the crystal structural parameters and the theoretical vibrational frequencies show good agreement with experimental values. On the basis of theoretical vibrational analyses, the thermodynamic properties (standard heat capacities, standard entropies, and standard enthalpy changes) of the title compound at different temperatures have been calculated, revealing the correlations between , , and temperatures. The total molecular dipole moment, mean linear polarizability and mean first hyperpolarizability obtained by calculation are 3.4724 Debye, 40.154 Å3 and 4.5424 × 10−29 cm5/esu, respectively. Three absorption bands in UV-VIS are mainly derived from the contribution of bands π → π* and electrons transfer from HOMO to LUMO, LUMO + 1, LUMO + 2, respectively.