New catalytic approach for nano-sized V(IV), Cr(III), Mn(II) and Fe(III)-triazole complexes: detailed spectral, electrochemical and analytical studies

A new series of metal ion complexes from a triazole-Schiff base was synthesized and fully characterized. The tridentate mode of coordination was the only mode of bonding in a 1:1 (M:L) molar ratio. Octahedral geometry was the only structural form proposed for all chelating compounds. This geometry was established based on UV-Vis, magnetic moments and ESR studies. The nanometer feature for all complexes was extracted from SEM images and XRD data. CV electrochemical study over Fe(III) and Mn(II) complexes (examples) displayed a i(p,c)/i(p,a) ratio over 1, which points to irreversible electrode couples. TGA and kinetic parameters reflect a best view about the thermal stability of all tested compounds. Molecular modeling was achieved through an advanced program, to optimize the structural forms and estimate significant parameters. All features concluded from all implemented studies orient us towards the best compounds serving in the intended catalytic application. Proceeding from this, Fe(III) and Mn(II) complexes were chosen for their heterogeneous catalytic application, as they can be used without treatment. Moreover, amounts from such complexes were ignited in open air (calcinations) to produce their corresponding oxides, Fe2O3 and MnO2. The synthesized oxides were fully analyzed to establish their chemical formula, as well as extract their morphological characters, which are the main players in the catalytic field. The surface characteristic and particulate sizes show promise in a catalytic role compared to other similar purchased oxides. The original complexes and their synthesized oxides were utilized separately to synthesize biodiesel from waste oils through heterogenous catalytic process. This process was conducted through a comparative study with other referenced methods. The catalytic role of prepared oxides was clearly observed whenever their original complexes did not display catalytic features as desired. Moreover, this comparative study was prolonged versus purchased oxides (Fe2O3 and MnO2) and the differentiation based on reaction yields after verification of physical features. The priorities of synthesized oxides in the catalytic process were impressive and confirm access to the desired goal.