Copolymeric Schiff Base Cu: A Platform for Active and Recyclable Catalyst in Aerobic Oxidations

Abstract

The synthesis of heterogeneous metal–ligand catalysts with high activity and good recyclability is always an important topic but still challenging to make. Herein, we reported a solid Schiff base Cu catalyst synthesized by incorporating Cu sites into the copolymeric Schiff base ligand, which is achieved from a porous polydivinylbenzene functionalized with Schiff base groups. A heterogeneous Schiff base Cu catalyst denoted as hetero-SchCu was obtained. Systemic characterizations involving XPS, FTIR, N2 sorption, and electronic microscopy demonstrate the structural features of hetero-SchCu including functionalized Schiff base ligand, stabilized and highly dispersed Cu species, and rich porosity. The hetero-SchCu exhibits high catalytic activity and selectivity in the oxidation of a series of alcohols and cyclohexane. Importantly, the hetero-SchCu is stable and recyclable in the tests involving several runs without a decrease in activity. This work not only demonstrates a platform for developing polymeric heterogeneous catalysts, but also provides efficient catalysts for the oxidation of alcohols and cyclohexane.

A manganese(iii) Schiff base complex immobilized on silica-coated magnetic nanoparticles showing enhanced electrochemical catalytic performance toward sulfide and alkene oxidation

“…[6][7][8][9] However, they suffer from some disadvantages such as the problem of separation and recovery from the reaction mixture at the end of the process. 10 Hence, designing catalytic systems of Schiff base complexes with easy recyclability is still a challenging task.…”

Nickel(II) Schiff base complex supported on nano‐titanium dioxide: A novel straightforward route for preparation of supported Schiff base complexes applying 2,4‐toluenediisocyanate

“…[8] So, for improving the efficiency of their catalytic activity and ease of separation from reaction media, scientists have tried to convert them into heterogeneous systems in various ways. In this light, several methods can be used, such as: (1) linking onto metal oxides such as silica, Fe 3 O 4 and so on, [9][10][11] (2) immobilizing on organic supports like graphene oxide [12,13] and carbon nanotubes, [14] (3) copolymerizing and incorporating into an organic polymer like chitosan or porous polydivinylbenzene [15][16][17][18][19] and (4) encapsulating in various zeolites. [20][21][22] Organosulfur compounds such as sulfoxides and sulfones are very important compounds in organic chemistry.…”

Optically Active Microspheres Containing Schiff Base: Preparation and Enantio-Differentiating Release toward Drug Citronellal

“…The applications of Schiff bases have received ever-increasing attention because the characteristic chemical bond [−(CN)−] has excellent ion coordinative capability , and pH-responsive ability . Schiff bases and their derivatives have been widely used for developing catalyst intermediates, , biological sterilizations, , fluorescent reagents, , self-assembled polymers, , and polymer stabilizers . More recently, it was reported that Schiff bases can be used as electrodes for batteries and used to prepare metal–organic frameworks (MOFs) , and covalent organic frameworks (COFs) .…”

“…SCB(−) ] as an example, the release process was carried out in the mixed solution (volume ratio, water/ethanol = 1/9) because the citronellal is only slightly soluble in water. The release systems were recorded as solution (pH 1,3,5,7,11). By UV−vis spectra analysis, the results are shown in Figure4.…”