Pyrene-Containing Polymer-Supported Cu/TEMPO Catalytic Systems: Aromatic Stacking-Enhanced Cooperative Catalysis

Abstract

Noncovalent immobilization of discrete molecular species on polymer supports is a unique approach to engineer multifunctional cooperative catalysts. Here we devise a modular strategy for the construction of polymersupported Cu/2,2,6,6-tetramethyl-1-piperidine-N-oxyl (TEMPO) catalytic systems by using hydrophobic interactions and aromatic stacking interactions. Polymer-supported Cu/TEMPO catalysts prepared by nanoprecipitation exhibit excellent catalytic activities for aerobic oxidation of benzyl alcohol, which can be tailored by the type of aromatic moieties, effective constituent ratios, and polymer compositions. We found that strong aromatic stacking interactions and the use of pyrene-containing polymers are crucial to enhance cooperativity. This modular strategy is promising for the immobilization of multifunctional cooperative catalysts with excellent catalytic activities and has potential for the engineering of other heterogeneous multifunctional catalysts.

Engineering of polystyrene-supported acid–base catalysts for aldol condensation in water

“…2). In agreement with reported results, 26,32 spherical nanoparticles with small size (o100 nm, Fig. 2A and C) were successfully prepared.…”

Cooperative catalysis of Cu/2,2,6,6-tetramethyl-1-piperidine-N-oxyl nanocatalysts supported by ultraviolet light-responsive polyimides

“…Polyimide containing NDI moieties ( P6 ) was synthesized and characterized in our previous works. 35 Catalytic components containing a pyrene group ( 1 , 2 , and 3 , Fig. 1) were synthesized via Cu( i )-catalyzed azide–alkyne cycloaddition reactions.…”

“…A Significant loss in activity was found while reusing the catalysts (Fig. S17†), 34–36 likely caused by degradation of intermediates derived from TEMPO. 38…”

“…To increase local concentrations of functional groups within nanocatalysts, aromatic stacking interactions were used for the construction of polymer-supported nanocatalysts. 35,36 NDI-based polyimides were used as supports for the immobilization of pyrenecontaining catalytic components via nanoprecipitation. 36 Although nanocatalysts with improved catalytic properties were prepared by using hydrophobic interactions and aromatic stacking interactions, more efforts are required to gain more insights into structure-activity relationships and develop strategies that can regulate cooperative behaviours.…”

“…1) were synthesized via Cu(I)-catalyzed azidealkyne cycloaddition reactions. 35 Azobenzene is well-known for its response to UV and visible light irradiations. To evaluate the responsive behaviour of polyimides containing azobenzene and NDI moieties, UV irradiations (λ = 365 nm) with different power and times were applied, and the transformation of trans-azobenzene to cis-azobenzene was monitored by UV-vis spectroscopy.…”