Electronic absorption spectroscopic behavior and acidity constants of some new dinitrophenylhydrazone derivatives.

In the present study, UV-visible electronic spectra of three new 2,4-dinitrophenylhydrazone derivatives (C1, C2 and C3) have been studied. Different bands observed have been assigned to the proper electronic transitions. The solvatochromic behaviors of these compounds were investigated by studying their electronic spectra in several organic solvents with different polarities. The longer wavelength band is assigned to an intermolecular charge transfer transition. The solvated H-bonding complexes formed between dimethylformamide and 2,4-dinitrophenylhydrazone derivatives were also investigated. ΔG, and the Kf values of the molecular complexes formed in solution have been determined. Effects of temperature increase and concentration changes on the longer spectroscopic wavelength band of the studied compounds were investigated. In this work, the behavior of acidity constants of these compounds in different pH values is studied by a multiwavelength spectrophotometric method too.