Abstract
We report the comparative synthetic methodologies and characterization of a tetradentate Schiff base ligand 1,2-(diimino-4′-antipyrinyl)-1,2-diphenylethane (DE). The target synthesis of oxovanadium(IV) and dioxouranium(VI) complexes (vanadyl and uranyl) with the (DE) ligand was also attempted to envisage the effect of metal ion steric factor on complexation process through solution phase thermodynamic and kinetic studies. The thermodynamic stabilities of synthesized vanadyl and uranyl (DE) complexes are discussed in light of their solution phase thermodynamic stability constants obtained by electroanalytical method. A comparative kinetic profile of vanadyl and uranyl complexation with DE is also reported. The complexation reaction proceeds with an overall 2nd order kinetics with both metal ions. Temperature dependent studies of rate constants present an activation energy barrier of ca. 40.913 and 48.661 KJ mol−1, for vanadyl and uranyl complexation, respectively, highlighting the metal ion steric and ligand preorganization effects. The synthesized Schiff base ligand and its vanadyl and uranyl complexes were screened for biocidal potential as antibacterial, antifungal, and anthelmintic agents with the results compared to corresponding reference drugs.
Highlights
Studies related to structure, reactivity, and applications of newly reported ligands and complexes form an imperative aspect of modern day inorganic chemistry
Schiff bases derived from the condensation of 4aminoantipyrine with diketones represent an interesting class of biologically important chelating ligands; metal complexes of these ligands are of great interest owing to their pharmacological and analytical applications [7,8,9,10,11]
The Schiff base 1,2(diimino-4-antipyrinyl)-1,2-diphenylethane (DE) was synthesised by the condensation of 1-phenyl-2,3-dimethyl-4aminopyrazol-5-one (4-aminoantipyrine) with 1,2-diphenylethane-1,2-dione using three synthetic methodologies. The efficacy of these methods was compared in terms of reaction time, percent yield, and energy demand (Table 1)
Summary
Reactivity, and applications of newly reported ligands and complexes form an imperative aspect of modern day inorganic chemistry. Schiff bases are one of the most widely used organic compounds and their metal complexes have a variety of biological, analytical and material applications in addition to their important roles in catalysis and organic synthesis [1,2,3,4,5,6]. Schiff bases derived from the condensation of 4aminoantipyrine with diketones represent an interesting class of biologically important chelating ligands; metal complexes of these ligands are of great interest owing to their pharmacological and analytical applications [7,8,9,10,11]. In embracing the principles of green chemistry [18,19,20], we depict a comparative account of the conventional and nonconventional synthetic protocols for the synthesis of Schiff base (DE) obtained from
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