Site-specific catalysis on a micro-catalytic chip by synergistic silencing of site-directing electronic effects of functional groups in aromatics

Abstract

We report a light-driven interface engineering of a microcatalytic chip comprising a PV₃W₉O₄₀ type component, MWCNTs and polypyrrole that enables unusual facile para nitration with high selectivity (95%). The chip is designed by simultaneously synthesizing the soft-oxometalate (SOM) pre-catalyst components and patterning them on a glass surface using microbubble lithography. The design reported involves interface engineering such that the exposure of the oxo-sites (of patterned SOMs) enables aromatic substrate anchoring. Such an anchoring silences the site-directing electronic effects of the functional groups in aromatics. This leads to unusual site selectivity leading to facile para-nitration with high selectivity (95%). The generality of this light driven catalyst design is demonstrated with a set of substrates that unequivocally demonstrate the silencing effect of the functional groups in aromatics. This technique can lead to an unprecedented methodology for the synthesis of any aromatic di-/tri-/multi-substitution otherwise difficult to achieve with high selectivity and atom economy, and that is sustainable in design.