Graphene Oxide Immobilized Copper(II) Schiff Base Complex [GO@AF‐SB‐Cu]: A Versatile Catalyst for Chan‐Lam Coupling Reaction

Abstract

Graphene oxide immobilized Cu(II) Schiff base complex, GO@AF‐SB−Cu, was synthesized by the reaction of a Schiff base functionalized Graphene oxide, GO@AF‐SB, with Cu(OAc)2.H2O in ethanol under reflux. The immobilized complex was isolated as a black‐coloured solid and characterized by various physico‐chemical techniques, such as Fourier transform infrared spectroscopy (FT‐IR), Fourier transform Raman spectroscopy (FT‐Raman), Powder X‐ray diffraction (PXRD), X‐ray photoelectron spectroscopy (XPS), Field emission scanning electron microscopy (FESEM), Energy dispersive X‐ray microscopy (EDX), Elemental mapping, Inductively coupled plasma atomic emission spectroscopy (ICP‐AES) and Thermo gravimetric analysis (TGA). The catalytic activity of the complex was explored in Chan‐Lam coupling reaction of amines and arylboronic acids without using any co‐catalyst or oxidant. Further, the catalyst could be easily recovered quantitatively from the reaction mixture by simple filtration and reused up to five times without significant loss in the catalytic activity. All the isolated organic products were characterized by 1H and 13C NMR spectroscopy.

Copper(II) complex intercalated graphene oxide nanocomposites as versatile, reusable catalysts for click reaction

“…The further satellite peaks for Cu 2p 3/2 and Cu 2p 1/2 were observed at 944 and 962 eV that indicates the +2 oxidation state of copper metal in the GO‐C1and GO‐C2 composite. [ 42–44 ]…”

Graphene Oxide Functionalized Zn(II) Salen Complex: An Efficient and New Route for the Synthesis of 1,2,3‐Triazole Derivatives

“…In the second FT‐IR spectrum corresponds to GO‐NH 2 (Figure b), the appearance of new broad peaks at 3438, 1602 cm −1 are assigned to the stretching and bending vibration of N−H bonds and the creation of new peaks at 1108 and 1045 cm −1 is attributed to the Si−O−Si and Si−O−C bonds and are the evidence for successful chemically immobilization of 3‐aminopropyltriethoxysilane ligand on the surface of GO . The third spectrum (Figure c) demonstrates a sharp peak at 1604 cm −1 and it is assigned to the imine and Schiff base formation (C=N) on the chemical structure of catalyst . The last spectrum related to the final catalyst (Figure d) indicated the blue shift and the peak corresponds to C=N group shifted from 1604 to 1595 cm −1 that approves the proper insertion of zinc ion into the Schiff base ligand .…”

“…So, the interlayer spacing from graphite to GO has been increased due to insertion functional groups such as hydroxyl, epoxy, and carboxyl . It is essential to mention that, our final catalyst (GO‐Salen‐Zn) has amorphous and irregular structure and did not have any clear peaks in XRD pattern …”

“…For example, Kumar and co‐workers reported the GO functionalized copper(II) Schiff base complex for the Chan‐Lam coupling reaction. Their new heterogeneous catalytic systems demonstrated higher catalytic efficiency in the synthesis of amine derivatives compared to simple copper salts . Ansari and colleagues used the same catalyst in the Suzuki‐Miyaura cross‐coupling reaction.…”

Synthesis, Characterization and Biological Evaluation of New Schiff Base Ligand derived from 3-hydroxy-benzaldehyde and p-toluidine and its Divalent Metal Ions

“…Biological activity probably conferred to them by the strong aromaticity of this ring system, which leads to great in vivo stability and generally, a lack of toxicity for higher vertebrates, including humans. Aside from these activities, Schiff bases also have other tremendous applications, they serves as dyes, agrochemicals, chemo sensor, catalyst, chemotherapeutic, anticorrosive, polymer [16][17][18][19][20][21]. Schiff bases have major concern in organic, inorganic, coordination, biochemistry and other material sciences [22].…”