Mannich base Cu(II) complexes as biomimetic oxidative catalyst

Synthesis of Cu(II) complexes by N,O‐donor ligand transformation and their catalytic role in visible‐light‐driven alcohol oxidation

“…Upon oxidation of the ligand, an anodic peak at Epa = +0.55 V was observed, showing the oxidation of the phenol, [ 72 ] whereas in the case of complexes shows an anodic peaks around Ep a = +1.10 V along with cathodic peaks around Ep c = +0.739 V, revealing a quasi‐reversible behavior of the complex due to the oxidation of phenolate ion to phenoxyl moiety (Figure S10). [ 24 ] Irreversible cathodic peak is observed in negative potential for both of the complexes at Epa = −1.06 V and Epa = −1.05 respectively, which indicates the reduction of Cu(II) to Cu(I). [ 73 ]…”

“…Benzyl alcohol has been taken as a substrate for alcohol oxidation, with a λ max (wavelength maxima) of 256 nm (π → π* transition). [ 24 ] In CH 2 Cl 2 solution, the catalytic mixture was subjected to perform UV–vis analysis after 0.5 h of interval. At beginning of the catalytic reaction, the absorbance around 400 nm (π → π* transition) due to the oxidized phenoxyl radical get sharply increased.…”

“…Reaction mixtures for the determination of hydrogen peroxide were prepared as per method described in our previous literature. [ 24 ]…”

“…Reaction mixtures for the determination of hydrogen peroxide were prepared as per method described in our previous literature. [24] After completion of catalytic reaction, an equal volume of water (1 ml) was added to the reaction mixture, and oxidized products (viz., benzaldehyde) were extracted with 3 Â 3 ml of DCM. After that, the aqueous layer was acidified with H 2 SO 4 (5.0 Â 10 À3 mol L À1 ) to pH $ 2 (examined by litmus paper) to stop further oxidation.…”

“…Sometimes at lower pH (~3.5), acetate group replaces the water. [ 24 ] These natural enzymes provide us the clues for how to go forward for greener catalytic systems based on bioinspired perception. It is also evident from the fact that, a N/O‐donor environment for copper ion can provide an ideal environment to shuttle between Cu(II) and Cu(I) state to act as an oxidation catalyst.…”