Synthesis and characterization for novel VO(II) complexes from cyanoacetohydrazide-based ligands; Hirshfeld crystals, DFT study and biodiesel catalytic synthesis from waste frying oil

Abstract

Two new VO(II) complexes have been synthesized from ligands based on cyanoacetohydrazide (H2L1 & H2L2). Variable analytical and spectral methods have elucidated these complexes as well as their original ligands. IR, 1H NMR, UV-Vis, Mass, EPR, SEM, EDX, XRD and elemental analysis were the practical techniques applied for characterization. Binegative tetradentate mode was suggested within (VO)2-L1 complex, while neutral tetradentate mode was suggested within (VO)2-H2L2 complex. The geometry of complexes was suggested according to VU-Vis spectra as well as EPR spectra to be a square-pyramidal form. In order to optimize their structural forms and extract critical quantum parameters, the DFT analysis was introduced under valence double-zeta polarized base set (6-31G*). The extracted physical parameters suggest that, the (VO)2-L1 complex has excellent characteristics. Hirshfeld's surface properties, on the other hand, indicate its distinctive crystal properties. The (VO)2-L1 complex was therefore selected to catalyze the synthesis of biodiesel via transesterification processes from waste frying oil. In particular, the physical characteristics and combustion efficiency of the synthesized biofuel suggest its high quality due to absence of Cd and Pb metals. The valuable goal attained in this study is to perform a catalytic function for selected VO(II) complex in preparing an economical product as a biofuel through a low cost and safe process.