Synthesis, Characterization, Electrochemical Properties, and DNA‐Binding Studies of Novel Schiff Base Metal Complexes: Catalysts in Transfer Hydrogenation of D‐Glucose‐Like Aldose Reductase Mimetics

In this study, the Schiff base (E)‐4‐chloro‐2‐(((4‐(phenylamino)phenyl)imino)methyl)phenol (Sadpa), obtained from the condensation reaction of 5‐chloro‐2‐hydroxybenzaldehyde and N 1 ‐phenylbenzene‐1,4‐diamine and reported for the first time in the literature, together with its Co(II) and Pd(II) complexes, was synthesized. The structure of the Schiff base was determined by spectroscopic methods such as elemental analysis, FT‐IR, 1 H/ 13 C‐NMR, and XRD, while the structures of the metal complexes were examined in detail using FT‐IR, UV–Vis, MS, thermal, and elemental analysis. Furthermore, the electrochemical behavior of both the Sadpa ligand and the Co(II) and Pd(II) complexes was investigated, as well as their potential interactions with DNA. The double cathodic peak observed in the Sadpa–Co and Sadpa–Pd complexes reveals the coexistence of both ligand and metal‐centered redox processes. It is observed that the Sadpa–Pd(II) complex exhibits more stable and higher affinity binding than the Co(II) complex. This indicates that factors such as coordination geometry and charge density of the metal center play a decisive role in the DNA‐binding behavior. In addition, the catalytic effects of the complexes in the transfer hydrogenation of D‐glucose to D‐sorbitol were investigated. The Sadpa–Pd(II) complex showed the most efficient and selective catalytic activity in the transfer hydrogenation of D‐glucose to D‐sorbitol under micorwave irradiation, with 97.98% selectivity for D‐sorbitol at 96.50% conversion, indicating that it can act as a mimetic of the aldose reductase enzyme. Mannitol was produced as the only by‐product in minor amounts during the catalysis.