Binapthyl Schiff base diamine complex covalently bonded to modified SBA-15: Synthesis, characterization and catalytic application

Protected mesoporous SBA-15 phase was synthesized by grafting the complex Chloro (S,S)(−)[N-3-tert-butyl-5-chloromethyl salicylidene]-N′-[3′,5′-di tert-butyl salicylidene] 1,1′-binapthyl-2,2′-diamine manganese(III) through the reactive 3-aminopropyl trimethoxysilane(3-APTMS) group. The surface properties of the functionalized catalyst were analyzed by a series of characterization techniques like elemental analysis, XRD, N2 sorption measurement isotherm, FT-IR, XPS, and solid state 13C NMR. The screening of the catalyst Mn(III)-L-SBA-15 and neat Mn(III)-L complexes was done for the oxidation reaction of thioanisole (methyl phenyl sulfide) using TBHP as an oxidant. Mn(III)-L-SBA-15 catalyst shows higher activities and exhibit enantiomeric excess comparable to homogeneous catalyst.

Graphical abstractMn(III)-L-SBA-15 complex. Mn(III)-L-SBA-15 = Chloro (S,S)(−)[N-3-tert-butyl-5-chloromethyl salicylidene]-N′-[3′,5′-di tert-butyl salicylidene] 1,1′-binapthyl-2,2′-diamine manganese(III) (homogeneous system) on modified SBA-15.Figure optionsDownload full-size imageDownload high-quality image (76 K)Download as PowerPoint slideHighlights► The synthesis of mesoporous SBA-15 was carried out hydrothermally under the autogeneous pressure of an autoclave. ► Surface modification of SBA-15 was achieved by a post synthesis grafting method. ► Grafting of complex Chloro (S,S)(−)[N-3-tert-butyl-5-chloromethyl salicylidene]-N′-[3′,5′-di tert-butyl salicylidene] 1,1′-binapthyl-2,2′-diamine manganese(III) inside the OH protected NH2-SBA-15 was done by covalent bonding. ► Sulfoxidation reaction of methyl phenyl sulfide over Neat Mn(III) complex and well immobilized complex Mn(III)-L-SBA-15 were compared with and without catalyst condition.