Catalytic evaluation of copper (II) N‐salicylidene‐amino acid Schiff base in the various catalytic processes

Abstract

N‐Salicylidene amino acid Schiff base sodium sulfonate salt, as a tridentate dibasic chelating ligand, was obtained from the common condensation of salicylaldehyde‐5‐sodium sulfonate with tyrosine (HPST). The internal formed ligand coordinated to Cu2+ ion in an aqueous media affording new Cu (II)‐complex (Cu‐PST), which characterized by various physico‐chemicals spectral tools. The mononuclear complex was evaluated as a homogeneous and heterogeneous catalyst in the (ep)oxidation protocols of 1,2‐cyclooctene and benzyl alcohol. Heterogeneously, Cu‐PST was immobilized on Fe3O4‐SiO2, as nanoparticles. The heterogeneous catalyst was characterized by infrared, X‐ray diffraction, scanning electron microscopy, transmission electron microscopy, energy‐dispersive spectroscopy, Brunauer−Emmett−Teller and magnetism. Homogeneously, the temperature, solvent and oxidant influences were examined in the catalytic reactions to realize the best reaction conditions. Cu‐catalyst exhibited better catalytic performance in the (ep)oxidation processes homogeneously than that in the heterogeneous phase at 80°C for 2 hr in acetonitrile. Reusability of the homogeneous catalyst was for a maximum of three times in the (ep)oxidation reaction, whereas the heterogeneous catalyst was active for six times. A mechanistic pathway was proposed for both catalysts, comparatively.

ZnO–TiO2 Nanoparticles Coated by the Dioxomolybdenum (VI) bis-Schiff Base Complex for Catalytic Oxidation of Sulfides

“…, nanocomposite, a specific band should be considered. The 4-OH band of the phenyl ring in MoO 2 L 2 disappeared after the immobilization process . This observation indicated the bonding of the 4-hydroxy group to ZnO–TiO 2 nanoparticles via its deprotonation process (Scheme ).…”

“… − italicln ( C C o ) = k t where C o is formatted for the reactant concentration (Ph 2 S) at the starting of the oxidation reaction and C is assigned for the remaining concentration of the reactant solution (Ph 2 S) at the given time ( t ). With eq (referring to the Arrhenius equation), E a was obtained for the catalytic system with MoO 2 L 2 or MoO 2 L 2 @ZnO–TiO 2 catalysts at different temperatures. The relationship between ln k versus 1/T could be utilized to estimate the E a values, as given in the following ln nobreak0em.25em⁡ k = italicln nobreak0em.25em⁡ A − E a normalR normalT where k , T , A , and R refer to the rate constant, the absolute temperature, the pre-exponential factor, and the gas constant, respectively.…”

The Oxidation Behavior of Potato Starch and Benzyl Alcohol via Peroxide in the Catalysis of Metal Complexes

“…The proposed mechanisms for the oxidation of PS or benzyl alcohol with H 2 O 2 , catalyzed by Schiff base metal (Co 2+ , Mn 2+ , Cr 3+ , Ru 3+ , VO 2+ ) complexes in an aqueous medium, are given Scheme . [ 50,51 ] In this demonstration, rather than the oxidation of metal cations, it is shown how peroxide interacts with metal ions to form metal oxides and how this metal oxide affects the substrate. Mixing of an aqueous H 2 O 2 with the metal complexes (in acetonitrile) might be led to oxidation of the complex catalyst to form an active species of Co 3+ , Mn 4+/7+ , Cr 5+/6+ , Ru 4+/5+ , and V 5+ = O ions ( A ) through electron transfer mechanism (Scheme 2).…”

“…The proposed mechanism for the oxidation of potato starch. [51] synthesized showed superior catalytic activity in starch oxidation compared to other methods. For example, many studies have used TEMPO as a catalyst for the oxidation of alcohol functions in polysaccharides.…”

Synthesis, Identification and Antibacterial Activities of Amino Acid Schiff Base Cu(II) Complexes with Chlorinated Aromatic Moieties

“…Schiff bases were discovered by Hugo Schiff, and their metal complex derivatives were largely synthesized, for example, incorporating amino acids [1]. Their fields of application are varied and concern, for example, environmental sensors [2], catalysis [3,4], and anticancer [5,6] or antioxidant agents, but they also serve as antimicrobial agents, particularly against bacterial and fungal pathogens, showing that, compared to Co(II), Ni(II) or Zn(II), Cu(II) complexes show lower MIC values, revealing that these complexes present a better growth inhibitory activity [7]. Other Schiff bases' copper complexes were described from salicylaldehyde derivatives and tested as antimicrobials [8,9], but in all the previous literature on amino acid copper-complex Schiff base syntheses [10], it is noticeable that the reaction time is somehow long, lasting from several hours to days.…”