Controlling Catalyst-Phase Selectivity in Complex Mixtures with Amphiphilic Janus Particles

Abstract

Amphiphilic Janus particles with catalyst selectively loaded on either the hydrophobic or hydrophilic region are promising candidates for efficient and phase-selective interfacial catalysis. Here, we report the synthesis and characterization of Janus silica particles with a hydrophilic silica domain and a silane-modified hydrophobic domain produced via a wax masking technique. Palladium nanoparticles were regioselectively deposited on the hydrophobic side and the phase selectivity of the catalytic Janus particles was established through kinetic studies of benzyl alcohol hydrodeoxygenation (HDO). These studies indicated that the hydrophobic moiety provided nearly 100x the catalytic activity as the hydrophilic side for benzyl alcohol HDO. The reactivity was linked to the anisotropic catalyst design through microscopy of the particles. The catalysts were used to achieve phase-specific compartmentalized hydrogenation and selective in-situ catalytic degradation of a model oily pollutant in a complex oil/water mixture.

The role of fibril structure and surface hydrophobicity in secondary nucleation of amyloid fibrils

“…The four hydrophobic residues that are exposed on the surface of the Aβ42 fibril core (Val18, Ala21, Val40, and Ala42) can be grouped into two hydrophobic patches, Val18+Ala21 and Val40+Ala42 ( 12 , 13 ). This arrangement is intriguing in light of the many systems (enzymes, interfacial catalysts, and beyond) where hydrophobic grooves, clefts, or surfaces have been inferred to affect catalysis either through enhanced substrate binding or through modulation of the catalytic activity ( 25 – 33 ). However, higher affinity does not always govern catalysis; the Sabatier principle states that there is an optimal substrate affinity above which reduced product release impedes catalysis and below which catalysis is reduced due to insufficient substrate binding ( 34 ).…”

Multiphase Microreactors Based on Liquid–Liquid and Gas–Liquid Dispersions Stabilized by Colloidal Catalytic Particles

“…[109] Janus silica particles with defined hydrophilic and silane-modified hydrophobic domains were impregnated with Pd either on the hydrophobic side or on the whole particles,s tabilizing water-in-decalin emulsions. [110] In [101][102][103][104][105] b) Hydrogenation of activated double bonds; [88,106,107,109] c) Hydrodeoxygenation of vanillin; [110a, 111, 112] d) Hydroformylation of alkenes; [113,114] e) Bio-photoreforming of alcohols; [115.116] f) Fischer-Tropsch synthesis. [117a] the former case,the rate constant for vanillin HDO is 2orders of magnitude higher,p ointing out an important role of the microenvironment on the catalytic performance.P d/Al 2 O 3 particles modified with organophosphonic acids and incorporating Brønsted acid centers can also stabilize water-indecalin emulsions and catalyze vanillin HDO with ayield up to 90 %a to nly 50 8 8Cf or 1h.…”

Highly Selective Catalysis at the Liquid–Liquid Interface Microregion

“…Although Janus particles that consist of a hydrophobic part and a hydrophilic part were successfully synthesized and can be assembled at Pickering emulsion interfaces 24,[50][51][52][53] , it is still di cult to control reaction locus on a microscale because it is very challenging to position catalytic sites selectively on one of the parts with nanometer sizes 50 . Fortunately, we unexpectedly found that the unique interaction between TNTs and TPPTS makes possible the spatially controlled assembly of TNTs at the droplet interface (Supplementary Fig.…”