Synthesis and Characterization of Some 3D Metals Complexes Derived from Schiff Base of Benzoin

https://doi.org/10.5281/zenodo.18599196

Abstract

We made a new Schiff base ligand by reacting benzoin with 4-aminophenol, then combined it with Ni(II), Cu(II), Zn(II), Mn(II), Co(II), and Mg(II) to get six different metal complexes. To check what we’d made, we looked at their melting points, measured conductivity, and ran FT-IR spectra.

The ligand itself is a brown, crystalline solid. It doesn’t dissolve in water but goes into ethyl acetate and hexane just fine. It shows almost no electrical conductivity (around 0.13 µS·cm⁻¹ in 1 mM MeOH), so it’s definitely non‑electrolytic. In the FT-IR spectrum, the carbonyl band from benzoin (about 1696 cm⁻¹) disappears and a new band pops up at 1568 cm⁻¹, which tells us the Schiff base formed like we planned.

When we added the metals, each complex came out as a colored solid—green with Ni and Cu, off-white with Zn, and a clay color for Mn, Co, and Mg. Their conductivities were all super low too (under 0.20 µS·cm⁻¹), so none of them act like electrolytes.

The FT-IR spectra gave us more to go on. The imine C=N band in the ligand, which shows up near 1570 cm⁻¹, shifts down to about 1420–1430 cm⁻¹ in the complexes, and new bands for metal–nitrogen bonds appear (Ni at 530 cm⁻¹, Cu at 433 cm⁻¹, Zn at 447 cm⁻¹, Mn at 486 cm⁻¹, Co and Mg both at 447 cm⁻¹). This shift matches what you’d expect if the metal binds through the azomethine nitrogen. A bunch of the complexes also show broad FT-IR bands between 2550 and 3615 cm⁻¹, which points to coordinated water.

All in all, the data confirm we made the Schiff base ligand and its complexes with these 3d metals.