2D Graphene Oxide Membrane Nanoreactors for Rapid Directional Flow Ring‐Opening Reactions with Dominant Same‐Configuration Products

Abstract Nanoconfinement within enzymes can increase reaction rate and improve selectivity under mild conditions. However, it remains a great challenge to achieve chemical reactions imitating enzymes with directional molecular motion, short reaction time, ≈100% conversion, and chiral conversion in artificial nanoconfined systems. Here, directional flow ring‐opening reactions of styrene oxide and alcohols are demonstrated with ≈100% conversion in <120 s at 22 °C using graphene oxide membrane nanoreactors. Dominant products have the same configuration as chiral styrene oxide in confined reactions, which is dramatically opposed to bulk reactions. The unique chiral conversion mechanism is caused by spatial confinement, limiting the inversion of benzylic chiral carbon. Moreover, the enantiomeric excess of same‐configuration products increased with higher alkyl charge in confined reactions. This work provides a new route to achieve rapid flow ring‐opening reactions with specific chiral conversion within 2D nanoconfined channels, and insights into the impact of nanoconfinement on ring‐opening reaction mechanisms.


Figure S2 .
Figure S2.C 1s XPS spectra of the GO, indicating the existence of surface oxygen-containing functional groups.The peaks at approximately 284.8, 286.8, 287.4 and 288.7 eV were attributed to the C-C, C-O, C=O (carbonyl C) and O=C-OH (carboxyl C) functional groups,

Figure S4. a )
Figure S4.a) Flow curves of reaction solution of styrene oxide and isopropyl alcohol corresponding to GO membranes with different thickness.Flow curves of reaction solution is nearly linear and reaction solution flow slows down nonlinearly with increasing GO membranes thickness.b) For GO membranes with different thicknesses, the corresponding slope of the reactant flow volume as a function of time, k.

Figure S6 .
Figure S6.SEM observation of cross-sections of the GO membrane with different thicknesses, showing compact multilayer structures.

Figure S7 .
Figure S7.Conversion of bulk reaction of styrene oxide with i-propanol catalyzed by GO nanosheets corresponding to time.The conversion of the bulk reaction increases with reaction time, and nearly complete conversion is achieved at ~270 min (~4.5 h).

Figure S8 .
Figure S8.Comparison of confined reactions and bulk reactions.(a-c) Conversion of confined ring-opening reactions between styrene oxide and ethanol (a), propanol (b), and isobutyl alcohol (c) as a function of GO membranes thickness.Nearly 100% conversion was achieved at the membrane thickness of 3.4 μm, 2.6 μm, and 1.7 μm, respectively.(d-f) Flow curves of reaction solution of styrene oxide and ethanol (d), propanol (e), and isobutyl alcohol (f) throughGO membranes with the thickness of 3.4 μm, 2.6 μm, and 1.7 μm, respectively.(g-i) Conversion of bulk ring-opening reactions of styrene oxide with ethanol (g), propanol (h), and isobutyl alcohol (i) catalyzed by GO nanosheets corresponding to time.

Figure S13 .
Figure S13.The HPLC traces of the permeation mixture obtained from the commercial (R)styrene oxide and isopropanol under confined reactions (top) or bulk reactions (bottom).As for confined reactions, the S/R enantiomeric ratio was determined to be 26:74 by chiral HPLC analysis while S/R enantiomeric ratio was determined to be 80:20 under bulk reactions (acetonitrile/water 4:6; flow rate 0.5 mL•min -1 ; λ = 205 nm; t(S) = 7.5 min; t(R) = 8.3 min).

Figure S14 .
Figure S14.Schematic illustration showing the difference about stereoselective reaction of (R)styrene oxide between confined reactions and bulk reactions.

Figure S18 .Figure
Figure S18.Percentage of (R)-product and (S)-product obtained under confined reactions, catalyzed by GO and GO-120 °C membranes.

Figure S20 .
Figure S20.Enantiomeric excess of ring-opening reactions between (S)-styrene oxide and isopropanol catalyzed by GO membranes and GO-120 °C membranes with thicknesses of 1.7 μm and 3.4 μm.

Figure S31 .
Figure S31.DFT calculations of electric charge of different alkyl-oxygen (RO) groups.

Figure S32 .
Figure S32.Enantiomeric excess of ring-opening reactions between S-styrene oxide and alkyl alcohols under bulk conditions as a function of electric charges of different RO substituents.