Multifunctional Integrated Compartment Systems for Incompatible Cascade Reactions Based on Onion-Like Photonic Spheres

Abstract

One of the central aims of synthetic biology and metabolic engineering is to mimic the integrality of eukaryotic cells to construct a multifunctional compartment system to perform multistep incompatible cascade reactions in a one-pot, controlled, and selective fashion. The key challenge is how to address the coexistence of antagonistic reagents and to incorporate these functionalities into an integrated system in a smart and efficient way. A novel strategy called “iterative etching–grafting” is proposed here based on monodispersed photonic spheres (PSs) prepared by microfluidics, which constructs a universal platform for incompatible cascade reactions. As a proof of concept, we spatiotemporally regulated the degree of etching of PSs, then grafted precursory groups of acid and base onto PSs, and incorporated a photocleavage method, which were capable of compartmentalizing the acid and base inside PSs. Utilizing the band-gap offsets of PSs could track the progress of cascade reactions in situ, and grafting various charged polymers on the surface of the pores by surface-initiated atom transfer radical polymerization (SI-ATRP) achieved the selectivity of the substrates, which flexibly constructed a multifunctional and integrated acid–base photonic multicompartment system (PMCS). The created PMCS shows excellent catalytic performance, convenient monitoring, and efficient substrate selectivity in the deacetalization–Knoevenagel cascade reaction. Furthermore, two types of electrophile/nucleophile PMCSs have also been accessibly constructed, demonstrating the facile generation of other incompatible systems with the versatility as well as the advancement and extensibility of the developed strategy.

Compartmentalization and Photoregulating Pathways for Incompatible Tandem Catalysis

“…Scientists have developed multicompartmental catalytic systems based on various strategies including the use of sol–gels, Pickering emulsion droplets, supramolecular metal complex architectures, , and polymers. , Catalytic frameworks fabricated from these materials have realized compartmentalization for multiple active catalytic sites, as epitomized by the cell, and enabled multistep nonorthogonal transformations. − ,− Incorporating responsive elements into the support structures has rendered them “smart”, i.e., allowing for reversible alterations of the physical and chemical properties in response to external stimuli such as temperature, , pH, light, , or enzymes. , The properties of the resulting smart materials impart an additional bioinspired control over single-step catalytic transformations. ,− Manipulation of multicatalytic tandem sequences, however, remains challenging and restricted to the regulation of reactivities via temperature actuation. , This limitation significantly affects the choice of catalysts and limits the feasibility of performing one-pot tandem catalysis at arbitrary temperature ranges. To date, no “smart” catalytic system can use or control different switchable states to tune and activate a desired synthetic pathway among many possible ones during a multistep synthesis.…”

Tandem Aldol Reaction from Acetal Mixtures by an Artificial Enzyme with Site-Isolated Acid and Base Functionalities

“…Examples include star polymers, magnetically separable catalysts, polymersomes, mesoporous materials, polymeric micelles, , microcapsules, graphene oxides, and hyper-cross-linked nanospheres . New materials continue to emerge in recent years such as hierarchically porous materials, monodispersed photonic spheres, and core–shell microparticles to address additional challenges in scale-up and introduce catalytic features mimicking those in biocatalysis.…”

In Situ Synthesis of Incompatible Polymers within Hollow Porous Organic Nanosphere Networks for Cascade Reactions

“…[13][14][15][16] Recently, a series of methods have been employed to overcome the abovementioned defect by means of the physical isolation of acid and base groups on catalyst supporters. [10,[17][18][19][20][21] For example, Yang et al marked the yolk-shell structured nanosphere possessing an acid shell (−SO 3 H) and a base core (−NH 2 ) by an organosilane-assisted selective corrosion method in order to catalyze a one-pot acidbase cascade reaction. [22] Corma and coworkers report a synthesis of functionalized porous polymeric aromatic framework materials with basic and acid groups so as to catalyze cascade-type reactions via a postmodification strategy.…”

“…[ 13–16 ] Recently, a series of methods have been employed to overcome the abovementioned defect by means of the physical isolation of acid and base groups on catalyst supporters. [ 10,17–21 ] For example, Yang et al. marked the yolk–shell structured nanosphere possessing an acid shell (−SO 3 H) and a base core (−NH 2 ) by an organosilane‐assisted selective corrosion method in order to catalyze a one‐pot acid–base cascade reaction.…”