Insight into the synthesis, structure affirmation and catalytic efficiency of divalent and trivalent metal chelates of mandelic acid hydrazone derivative

Abstract

The current work reports the synthesis of Cr(III), Mn(II), Co(II), Ni(II) and Cu(II) chelates of the Schiff base ligand named hydroxy-phenyl-acetic acid (2-hydroxy-naphthalen-1-ylmethylene)-hydrazide with multi-chelation centre toward metal ions. The spectral tools, ¹H-NMR, FTIR, mass, UV-vis spectra, and the analytical elemental and thermal analysis, in addition to magnetic moment and conductivity measurements all combined have been applied to conclude the structure and geometry of the synthesized metal complexes. The formed metal chelates have been assured to be formed with the molar compositions of 1 L : 1 M for PANH-Cr, PANH-Mn, PANH-Co, PANH-Ni and 2 L : 1 M for PANH-Cu. All the complexes have been confirmed to be non-electrolytic except the PANH-Mn and PANH-Ni which are 1 : 1 electrolytes. FTIR spectral analysis assured the ligand to act as mono basic bi or tridentate ligand leading to the formation of octahedral complexes with all metals except Cu(II) complex which assured to has square planar structure. Except PANH-Cr, all the synthesized metal chelates exhibited phenoxazinone synthase like efficacy with varying activity with dramatically high activity for PANH-Mn complex with TOF number of 169.89 h⁻¹.