Synthesis of novel immobilized tridentate Schiff base dioxomolybdenum(VI) complexes as efficient and reusable catalysts for epoxidation of unfunctionalized olefins

Chiral MnIII (Salen) Immobilized on Organic Polymer/Inorganic Zirconium Hydrogen Phosphate Functionalized with 3-Aminopropyltrimethoxysilane as an Efficient and Recyclable Catalyst for Enantioselective Epoxidation of Styrene

“…There are major peaks with binding energies of 642.1 and 653.2 eV , which correspond to Mn 2 P 3/2 and 2P 1/2 . A similar shift has also been reported earlier, where chiral salen Mn III catalysts and Schiff bases were immobilized on an amine modified ZPS-PVPA through N–Mn bonding [ 17 , 21 ].…”

Olefin epoxidation catalyzed by Schiff base molybdenum (VI) complexes immobilized onto zirconium poly (styrene-phenylvinylphosphonate)-phosphate

“…The bands at 268 nm and 510 nm were assigned to the π-π* transition of the phenyl groups and the d-d transition of MoO 2 (acac) 2 , respectively. The band at 398 nm was due to the ligand-to-metal charge transfer transition; MoO 2 (acac) 2 and MO 2 Ar/ZAPS-PVPA show similar bands at 268, 332 and 398 nm, which is in accordance with the presence of the proposed MoO 2 molybdenum (VI) species on the surface [10,12].…”

“…The bands at 268 nm and 510 nm were assigned to the π-π* transition of the phenyl groups and the d-d transition of MoO 2 (acac) 2 , respectively. The band at 398 nm was due to the ligand-to-metal charge transfer transition; MoO 2 (acac) 2 and MO 2 Ar/ZAPS-PVPA show similar bands at 268, 332 and 398 nm, which is in accordance with the presence of the proposed MoO 2 molybdenum (VI) species on the surface [10,12].A key to a better understanding is the X-ray photoelectron spectroscopy (XPS) investigations of the immobilized Schiff base molybdenum complexes, as they are sensitive to the surface and provide information about the electronic state of Mo. As shown in Fig.…”

“…With these points in mind, a new type of polystyrene-zirconium phosphate composite material (ZPS-PVPA) which has special new characteristics, such as possessing caves, holes, micropores, channels and secondary channels with various sizes and shapes by appropriate modification process of the polystyrene part was prepared. In previous work, we have reported the chiral salen Mn (III) complex axially immobilized onto diamine or polyamine and phenoxyl-modified ZPS-PVPA and their use in catalytic epoxidation, which exhibited great activity and enantioselectivity in the asymmetric epoxidation of unfunctionalized olefins [10][11][12][13]. In order to heterogenize conventional molybdenum catalysts, we have studied the preparation and catalytic activity of a molybdenum (VI)-supported modified ZPS-PVPA.…”

“…In order to heterogenize conventional molybdenum catalysts, we have studied the preparation and catalytic activity of a molybdenum (VI)-supported modified ZPS-PVPA. High conversion and epoxide selectivity from olefins were achieved with tert-butyl hydroperoxide and polystyrene-zirconium phosphate composite material-supported molybdenum (VI) catalyst, with no noticeable leaching of molybdenum from the support [12]. Especially, up to 99% ee values were obtained in the epoxidation of α-methylstyrene, which don't involved any costly chiral ligand or additives, while the catalysts only effectively promote the process of catalytic reactions.…”