Symmetry Breaking and Autocatalytic Amplification in Soai Reaction Confined within UiO-MOFs under Heterogenous Conditions.

Abstract

Symmetry breaking is observed in the Soai reaction in a confinement environment provided by zirconium-based UiO-MOFs used as crystalline sponges. Subsequent reaction of encapsulated Soai aldehyde with Zn(i-Pr)2 vapour promoted absolute asymmetric synthesis of the corresponding alkanol. ATR-IR and NMR confirm integration of aldehyde into the porous material, and a similar localization of newly formed chiral alkanol after reaction. Despite the confinement, the Soai reaction exhibits significant activity and autocatalytic amplification. Comparative catalytic studies with various UiO-MOFs indicate different outcomes in terms of enantiomeric excess, handedness distribution of the product and reaction rate, when compared to pristine solid Soai aldehyde, while the crystalline MOF remains highly stable to action of Zn(iPr)2 vapour. This is an unprecedented example of absolute asymmetric synthesis using MOFs.